Method for preparing iron phosphate from lateritic nickel ore hydrometallurgical slag

Abstract

A method for preparing iron phosphate from lateritic nickel ore hydrometallurgical slag, which obtains a high-purity ferrous ferric oxide intermediate product by means of phase regulation-reduction roasting-magnetic separation, as well as wet leaching-co-precipitation, to prepare a high-purity iron phosphate product. This method realizes high-value utilization of iron in lateritic nickel ore hydrometallurgical slag, and better solves environmental problems caused by long-term storage and landfilling of lateritic nickel ore hydrometallurgical slag; the prepared iron phosphate product can be used for the preparation of lithium iron phosphate batteries, which has high economic benefits, and is conducive to promotion and application; moreover, the obtained non-magnetic substances can be used to produce building materials, cement and other additional products, and the filtrate from the precipitation reaction can be used to produce ammonium salt by-products, thereby further maximizing the utilization of lateritic nickel ore resources.

Description

A method for preparing iron phosphate from 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 method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag. Background Art

[0002] Nickel sulfide and nickel oxide deposits are the world's major nickel deposits. Nickel oxide deposits account for 70% of total 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 total nickel reserves, leading to its development and utilization receiving increasing attention. The acid-leaching 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. Existing hydrometallurgical slag from laterite nickel ore has a low utilization rate, a complex process, high costs, and is not conducive to environmental protection. Furthermore, the iron content in laterite nickel ore leaching residue can reach 46-58 wt.%. Efficiently recovering the iron in this hydrometallurgical slag can significantly reduce iron resource waste and environmental pollution, achieving high-value, comprehensive utilization of laterite nickel ore.

[0004] Iron phosphate is one of the primary raw materials for preparing cathode materials for lithium iron phosphate batteries. For years, due to its improved conductivity, thermal stability, and recyclability, it has become a key electrode material for electric vehicle batteries. As consumption of lithium iron phosphate batteries increases, so too does demand, leading to a rapid increase in the demand for iron sources. However, the raw materials currently used to prepare iron phosphate are primarily high-purity iron or iron salts, resulting in high costs.

[0005] In summary, there is a need to develop a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag.

[0006] Summary of the Invention

[0007] 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.

[0008] In view of the problems existing in the prior art, the present application provides a method for preparing iron phosphate from laterite nickel ore hydrometallurgical slag, wherein the laterite nickel ore hydrometallurgical slag is first mixed evenly with a phase control agent and subjected to phase control heat treatment, so that the iron in the laterite nickel ore hydrometallurgical slag can be further enriched, and then a high-purity ferroferric oxide intermediate product is obtained by reduction roasting and magnetic separation, and finally a high-purity iron phosphate product is obtained by combining wet leaching and coprecipitation. The method described in the present application realizes the high-value utilization of iron in laterite nickel ore hydrometallurgical slag, better solves the environmental problems caused by long-term storage and landfill of laterite nickel ore hydrometallurgical slag; the prepared iron phosphate product can be used for the preparation of lithium iron phosphate batteries, has high economic benefits, and is conducive to promotion and application; moreover, the obtained non-magnetic material can be used to produce additional products such as building materials and cement, and the filtrate of the precipitation reaction can be used to produce ammonium salt by-products, thereby further improving the maximum utilization of laterite nickel ore resources.

[0009] To achieve this goal, this application adopts the following technical solutions:

[0010] The purpose of this application is to provide a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag, the method comprising the following steps:

[0011] (1) uniformly mixing laterite nickel ore hydrometallurgical slag with a phase control agent, and performing phase control heat treatment to obtain a phase control product;

[0012] (2) crushing and finely grinding the regulated phase product of step (1), uniformly mixing it with a reducing agent and a flux, and performing reduction roasting to obtain a reduced product;

[0013] (3) crushing and finely grinding the reduction product of step (2), adding a solvent for slurry preparation, and separating the product by magnetic separation to obtain a magnetic substance and a non-magnetic substance;

[0014] (4) uniformly mixing the magnetic substance described in step (3) with the acid leaching solution and the oxidant, performing a leaching reaction, and obtaining an iron salt solution through solid-liquid separation;

[0015] (5) adding the iron salt solution in step (4) to a phosphorus source precipitant to carry out a precipitation reaction, and obtaining an iron phosphate product through solid-liquid separation.

[0016] The method described in the present application is based on the theoretical knowledge of phase diagrams. First, the laterite nickel ore hydrometallurgical slag is evenly mixed with a phase control agent and subjected to phase control heat treatment to partially convert ferric oxide into ferroferric oxide, which can further enrich the iron in the laterite nickel ore hydrometallurgical slag. Then, a high-purity ferroferric oxide intermediate product is obtained through reduction roasting and magnetic separation. Finally, a high-purity ferric phosphate product is obtained by combining wet leaching and co-precipitation.

[0017] The method described in the present application realizes the high-value utilization of iron in laterite nickel ore hydrometallurgical slag, and better solves the environmental problems caused by long-term storage and landfill of laterite nickel ore hydrometallurgical slag; the prepared iron phosphate product can be used for the preparation of lithium iron phosphate batteries, and can also be used for the preparation of catalysts and ceramics, etc., with high economic benefits, which is conducive to promotion and application; moreover, the obtained non-magnetic material can be used to produce building materials and cement and other additional products, and the filtrate of the precipitation reaction can be used to produce ammonium chloride or ammonium sulfate products, which can be used in the manufacture of medicines, dry cell batteries, textile printing and dyeing, detergents, etc., thereby further improving the maximum utilization of laterite nickel ore resources.

[0018] 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.

[0019] In one embodiment, the laterite-nickel ore hydrometallurgical slag in step (1) is limonitic laterite-nickel ore hydrometallurgical slag.

[0020] In one embodiment, the dry basis composition of the laterite nickel ore hydrometallurgical slag in step (1) satisfies the following: TFe 46-58 wt.%, SiO2 1.4-5.4 wt.%, MgO 1.2-5.2 wt.%, Al2O3 5.9-9.9 wt.%, and CaO 1.1-4.1 wt.%.

[0021] 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.

[0022] As an optional technical solution of the present application, before the mixing in step (1), the laterite nickel ore hydrometallurgical slag is dried, crushed and finely ground in sequence, specifically comprising: placing the limonitic laterite nickel ore hydrometallurgical slag in a drying oven, setting a certain range of temperature gradient and insulation time for drying treatment, and crushing and finely grinding the dried material in a crusher to obtain fine slag powder with a certain particle size range.

[0023] In one embodiment, the drying temperature is 80-160°C, for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C, and the drying time is 600-1800 min, for example, 600 min, 800 min, 1000 min, 1100 min, 1300 min, 1500 min, 1600 min or 1800 min, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0024] In one embodiment, the target particle size of the crushing and fine grinding is 150-250 mesh, for example, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh or 250 mesh, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0025] As a preferred technical solution of the present application, the phase control agent in step (1) includes any one of CaO, SiO2, Al2O3 or MgO, or a combination of at least two of them.

[0026] In one embodiment, the amount of the phase control agent added in step (1) is 10-25% by mass of the dry basis of the laterite nickel ore hydrometallurgical slag, for example, 10%, 12%, 15%, 16%, 18%, 20%, 22% or 25%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] As an optional technical solution of the present application, the heating rate of the phase-controlled heat treatment in step (1) is 1-5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min or 5°C / min, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0028] In one embodiment, the target temperature of the phase regulation heat treatment in step (1) is 600-1400°C, for example, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C or 1400°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0029] In one embodiment, the holding time of the phase regulation heat treatment in step (1) is 180-420 min, for example, 180 min, 200 min, 230 min, 250 min, 280 min, 300 min, 320 min, 350 min, 370 min, 400 min or 420 min, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0030] It should be noted that in the present application, the laterite nickel ore hydrometallurgical slag is evenly mixed with the phase control agent, and the obtained mixed fine slag powder is placed in a graphite crucible or a corundum crucible, covered, and placed in a high-temperature box furnace for phase control heat treatment. A certain range of heating rate, temperature gradient and holding time are set to obtain a controlled phase product.

[0031] As an optional technical solution of the present application, the target particle size of the crushing and fine grinding in step (2) is 150-250 mesh, for example, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh or 250 mesh, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] In one embodiment, the reducing agent in step (2) includes a carbonaceous reducing agent having a carbon content of 70-100 wt.%, such as anthracite, coke, lignite, etc., and the added amount accounts for 5-15% by mass of the regulated phase product, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0033] In one embodiment, the flux in step (2) includes sodium carbonate and / or potassium carbonate, and the added amount accounts for 10-20% by mass of the regulated phase product, for example, 10%, 12%, 15%, 17% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0034] In one embodiment, the heating rate of the reduction roasting in step (2) is 1-5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min or 5°C / min, 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 target temperature of the reduction roasting in step (2) is 600-1200°C, for example, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C or 1200°C, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0036] In one embodiment, the holding time of the reduction roasting in step (2) is 30-90 min, for example, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0037] It should be noted that in the present application, the regulated phase product after crushing and fine grinding is evenly mixed with a reducing agent and a flux, and the obtained mixed fine slag powder is placed in a graphite crucible or a corundum crucible, covered, and placed in a high-temperature box furnace for reduction roasting. A certain range of heating rate, temperature gradient and holding time are set to obtain a reduced product, and then the reduced product is cooled by a conventional cooling method (such as water cooling, air cooling or furnace cooling, etc.), and then placed in a crusher for crushing and fine grinding.

[0038] As an optional technical solution of the present application, the target particle size of the crushing and fine grinding in step (3) is 150-250 mesh, for example, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh or 250 mesh, 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 amount of the solvent added in the slurry adjustment treatment in step (3) is 1-2 times the mass of the reduction product, for example, 1 times, 1.1 times, 1.3 times, 1.5 times, 1.7 times, 1.9 times or 2 times, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0040] In one embodiment, the solvent in step (3) comprises water.

[0041] In one embodiment, the magnetic separation intensity of the magnetic separation in step (3) is 1500-3500Gs, for example, 1500Gs, 1700Gs, 2000Gs, 2300Gs, 2500Gs, 2800Gs, 3000Gs, 3300Gs or 3500Gs, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0042] In one embodiment, the non-magnetic material in step (3) is used for the production of building materials and / or cement.

[0043] It should be noted that the present application uses a magnetic separator for magnetic separation. By setting a certain range of magnetic separation intensity, magnetic and non-magnetic substances can be selected, and the magnetic and non-magnetic substances are filtered and dried respectively. The non-magnetic substances separated after magnetic separation are processed by simple conventional methods and can be used to produce building materials and cement products, etc.

[0044] As an optional technical solution of the present application, the acid leaching solution in step (4) includes a hydrochloric acid solution or a sulfuric acid solution with a mass concentration of 80-200 g / L, that is, a hydrochloric acid solution with a mass concentration of 80-200 g / L or a sulfuric acid solution with a mass concentration of 80-200 g / L.

[0045] In one embodiment, the oxidant in step (4) comprises hydrogen peroxide with a mass concentration of 60-200 g / L.

[0046] In one embodiment, the solid-to-liquid ratio of the leaching reaction in step (4) is 1:(1-2) g / mL, for example, 1:1 g / mL, 1:1.3 g / mL, 1:1.5 g / mL, 1:1.8 g / mL or 1:2 g / mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0047] It should be noted that the volume of the liquid phase in the solid-liquid ratio of the leaching reaction described in this application is the sum of the volumes of the acid leaching solution and the oxidant, and the volume ratio of the acid leaching solution to the oxidant is (1-5):1.

[0048] In one embodiment, the leaching temperature of the leaching reaction in step (4) is 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0049] In one embodiment, the leaching time of the leaching reaction in step (4) is 30-180 min, for example, 30 min, 50 min, 80 min, 100 min, 130 min, 150 min or 180 min, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0050] In one embodiment, the stirring rate of the leaching reaction in step (4) is 80-300 rpm, for example, 80 rpm, 100 rpm, 130 rpm, 150 rpm, 170 rpm, 200 rpm, 220 rpm, 250 rpm, 270 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.

[0051] It should be noted that, in this application, an acid leaching solution in a certain concentration range is added to the obtained magnetic material as a leaching agent and an oxidant, and the solid-liquid ratio, leaching temperature, leaching time and stirring rate are controlled within a certain range. Under this condition, an iron salt solution (ferric sulfate solution or ferric chloride solution) can be obtained.

[0052] As an optional technical solution of the present application, the phosphorus source precipitant in step (5) includes a phosphoric acid aqueous solution with a mass concentration of 100-300 g / L.

[0053] In one embodiment, the volume ratio of the iron salt solution to the phosphorus source precipitant in step (5) is 1:(0.9-2.0), for example, 1:0.9, 1:1.0, 1:1.2, 1:1.5, 1:1.6, 1:1.8 or 1:2.0, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0054] In one embodiment, the pH of the precipitation reaction system in step (5) is controlled to be 2.5-3.5, for example, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4 or 3.5, 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 precipitation reaction in step (5) is performed using aqueous ammonia with a mass concentration of 100-300 g / L to control the pH.

[0056] In one embodiment, the temperature of the precipitation reaction in step (5) is 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0057] In one embodiment, the precipitation reaction time in step (5) is 30-120 min, for example, 30 min, 40 min, 50 min, 60 min, 80 min, 100 min or 120 min, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0058] In one embodiment, the stirring rate of the precipitation reaction in step (5) is 80-300 rpm, for example, 80 rpm, 100 rpm, 130 rpm, 150 rpm, 170 rpm, 200 rpm, 220 rpm, 250 rpm, 270 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.

[0059] It should be noted that in this application, a phosphorus source precipitant in a certain concentration range is added to the obtained iron salt solution, the volume ratio, precipitation temperature, precipitation time and stirring rate are controlled in a certain range, and ammonia water in a certain concentration range is used to regulate the pH during the precipitation reaction. It can ensure that the solid (ferric phosphate) and the liquid (ammonium chloride or ammonium sulfate solution) are separated, and the obtained solid is placed in a drying oven, and a certain range of temperature and time are set to obtain an iron phosphate product. The ammonium chloride or ammonium sulfate solution undergoes a series of crystallization treatments to obtain an ammonium chloride or ammonium sulfate product. The obtained iron phosphate can be used to manufacture lithium iron phosphate battery materials, catalysts and ceramics, etc. The obtained ammonium chloride or ammonium sulfate products can be used to manufacture medicines, dry cells, textile printing and dyeing, detergents, etc.

[0060] As an optional technical solution of the present application, the solid obtained by the solid-liquid separation in step (5) is dried to obtain the ferric phosphate product.

[0061] In one embodiment, the drying temperature is 80-160°C, for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C, and the drying time is 60-240 min, for example, 60 min, 80 min, 100 min, 120 min, 150 min, 170 min, 200 min, 210 min, 220 min or 240 min, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0062] In one embodiment, the mother liquor obtained by the solid-liquid separation in step (5) is subjected to crystallization to obtain an ammonium salt product, such as ammonium chloride or ammonium sulfate product.

[0063] Compared with the existing technical solutions, this application has at least the following beneficial effects:

[0064] (1) The method described in the present application is based on the theoretical knowledge of phase diagrams. First, the laterite nickel ore hydrometallurgical slag is uniformly mixed with a phase control agent and subjected to phase control heat treatment, which can further enrich the iron in the laterite nickel ore hydrometallurgical slag. Then, a high-purity ferroferric oxide intermediate product is obtained by reduction roasting and magnetic separation. Finally, a high-purity ferric phosphate product is obtained by combining wet leaching and coprecipitation.

[0065] (2) The method described in the present application realizes the high-value utilization of iron in laterite nickel ore hydrometallurgical slag, and better solves the environmental problems caused by long-term storage and landfill of laterite nickel ore hydrometallurgical slag;

[0066] (3) The iron phosphate product prepared by the method described in the present application can be used for the preparation of lithium iron phosphate batteries, and can also be used for the preparation of catalysts and ceramics, etc., which has high economic benefits and is conducive to promotion and application; moreover, the non-magnetic substance obtained can be used to produce building materials and cement and other additional products, and the filtrate of the precipitation reaction can be used to produce ammonium chloride or ammonium sulfate products, which can be used to manufacture medicines, dry batteries, textile printing and dyeing, detergents, etc., thereby further improving the maximum utilization of laterite nickel ore resources.

[0067] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] 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.

[0069] FIG1 is a process flow chart of the method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag described in the present application. DETAILED DESCRIPTION

[0070] The technical solution of the present application will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0071] 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:

[0072] The present application provides a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag, the process flow chart of which is shown in FIG1 . The method comprises the following steps:

[0073] (1) crushing and finely grinding laterite nickel ore hydrometallurgical slag, uniformly mixing with a phase control agent, and performing phase control heat treatment to obtain a phase control product;

[0074] (2) crushing and finely grinding the regulated phase product of step (1), uniformly mixing it with a reducing agent and a flux, and performing reduction roasting to obtain a reduced product;

[0075] (3) crushing and finely grinding the reduction product of step (2), adding a solvent for slurry preparation, and separating the product by magnetic separation to obtain a magnetic substance and a non-magnetic substance; the non-magnetic substance is used for the production of building materials and / or cement;

[0076] (4) uniformly mixing the magnetic substance described in step (3) with the acid leaching solution and the oxidant, performing a leaching reaction, and obtaining an iron salt solution through solid-liquid separation;

[0077] (5) adding the iron salt solution in step (4) to a phosphorus source precipitant to carry out a precipitation reaction, and obtaining an iron phosphate product through solid-liquid separation, and performing crystallization treatment on the mother liquor obtained by the solid-liquid separation to obtain an ammonium salt product.

[0078] Example 1

[0079] This embodiment provides a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag, the method comprising the following steps:

[0080] (1) placing the laterite nickel ore hydrometallurgical slag in a drying oven and drying it at 80° C. for 600 min, placing the dried material in a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 150 mesh, adding CaO as a phase control agent, wherein the amount of the phase control agent added is 10% by weight of the dry basis of the laterite nickel ore hydrometallurgical slag, mixing well, placing the mixture in a crucible, covering the mixture, and placing the mixture in a high-temperature box-type furnace for phase control heat treatment, setting the heating rate to 1° C. / min, the target temperature to 600° C., and the holding time to 180 min to obtain a phase control product;

[0081] 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 1.4-5.4wt.%, MgO 1.2-5.2wt.%, Al2O3 5.9-9.9wt.%, and CaO 1.1-4.1wt.%;

[0082] (2) placing the regulated phase product of step (1) into a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 150 mesh, and uniformly mixing it with coke as a reducing agent and sodium carbonate as a flux, wherein the amount of the reducing agent added accounts for 5% by mass of the regulated phase product, and the amount of the flux added accounts for 10% by mass of the regulated phase product. The mixed fine slag powder obtained by mixing is placed in a crucible, covered, and placed in a high-temperature box furnace for reduction roasting, setting the heating rate to 1°C / min, the target temperature to 600°C, and the holding time to 30min to obtain a reduced product;

[0083] (3) After cooling the reduction product of step (2), the reduction product is placed in a crusher for crushing and fine grinding to obtain fine slag powder with a target particle size of 150 mesh, and water is added for slurry preparation. The amount of water added is 1 times the mass of the reduction product. The magnetic separation intensity is set to 1500 Gs, and magnetic separation is performed in a magnetic separator to obtain magnetic material and non-magnetic material, and the magnetic material and non-magnetic material are filtered and dried respectively;

[0084] The non-magnetic material can be used to produce building materials and cement products after being processed by simple conventional treatment methods;

[0085] (4) adding a hydrochloric acid solution with a concentration of 80 g / L as an acid leaching solution and a hydrogen peroxide solution with a mass concentration of 60 g / L as an oxidant to the magnetic substance in step (3) and mixing them uniformly, controlling the solid-liquid ratio to be 1:1 g / mL, the leaching temperature to be 60° C., the leaching time to be 30 min, and the stirring rate to be 80 rpm, performing a leaching reaction, and obtaining an iron salt solution, specifically a ferric chloride solution, by solid-liquid separation;

[0086] (5) adding the iron salt solution of step (4) to a phosphoric acid aqueous solution having a mass concentration of 100 g / L as a phosphorus source precipitant to carry out a precipitation reaction, controlling the volume ratio of the two to be 1:0.9, the temperature to be 60° C., the time to be 30 min, and the stirring rate to be 80 rpm; and simultaneously adding ammonia water having a concentration of 100 g / L during the precipitation reaction to control the pH of the reaction system to be 2.5, drying the solid obtained by solid-liquid separation at 80° C. for 60 min to obtain an iron phosphate product, and subjecting the ammonium chloride solution obtained by solid-liquid separation to a series of crystallization treatments to obtain an ammonium chloride product.

[0087] The iron phosphate products obtained can be used to manufacture lithium iron phosphate battery materials, catalysts and ceramics, etc.; the ammonium chloride products obtained can be used to manufacture medicines, dry batteries, textile printing and dyeing, detergents, etc.

[0088] Example 2

[0089] This embodiment provides a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag, the method comprising the following steps:

[0090] (1) placing the laterite nickel ore hydrometallurgical slag in a drying oven and drying it at 120° C. for 1200 min, placing the dried material in a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 200 mesh, adding CaO as a phase control agent, wherein the amount of the phase control agent added accounts for 15% by mass of the dry basis of the laterite nickel ore hydrometallurgical slag, mixing well, placing the mixture in a crucible, covering the mixture, and placing the mixture in a high-temperature box-type furnace for phase control heat treatment, setting the heating rate to 3° C. / min, the target temperature to 1000° C., and the holding time to 300 min to obtain a phase control product;

[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 1.4-5.4wt.%, MgO 1.2-5.2wt.%, Al2O3 5.9-9.9wt.%, and CaO 1.1-4.1wt.%;

[0092] (2) placing the regulated phase product of step (1) into a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 200 mesh, and uniformly mixing it with coke as a reducing agent and sodium carbonate as a flux, wherein the amount of the reducing agent added accounts for 10% by mass of the regulated phase product, and the amount of the flux added accounts for 15% by mass of the regulated phase product. The mixed fine slag powder obtained by mixing is placed in a crucible, covered, and placed in a high-temperature box furnace for reduction roasting, setting the heating rate to 3°C / min, the target temperature to 900°C, and the holding time to 60min to obtain a reduced product;

[0093] (3) After cooling the reduction product of step (2), the reduction product is placed in a crusher for crushing and fine grinding to obtain fine slag powder with a target particle size of 200 mesh, and water is added for slurry preparation. The amount of water added is 1.5 times the mass of the reduction product. The magnetic separation intensity is set to 2500 Gs, and magnetic separation is performed in a magnetic separator to obtain magnetic material and non-magnetic material, and the magnetic material and non-magnetic material are filtered and dried respectively;

[0094] The non-magnetic material can be used to produce building materials and cement products after being processed by simple conventional treatment methods;

[0095] (4) adding a sulfuric acid solution with a concentration of 140 g / L as an acid leaching solution and a hydrogen peroxide solution with a mass concentration of 130 g / L as an oxidant to the magnetic material in step (3) and mixing them uniformly, controlling the solid-liquid ratio to be 1:1.5 g / mL, the leaching temperature to be 80° C., the leaching time to be 90 min, the stirring rate to be 190 rpm, carrying out a leaching reaction, and obtaining an iron salt solution, specifically a ferric sulfate solution, by solid-liquid separation;

[0096] (5) adding the iron salt solution of step (4) to a phosphoric acid aqueous solution having a mass concentration of 200 g / L as a phosphorus source precipitant to carry out a precipitation reaction, controlling the volume ratio of the two to be 1:1.5, the temperature to be 80° C., the time to be 60 min, and the stirring rate to be 190 rpm; and simultaneously adding ammonia water having a concentration of 200 g / L during the precipitation reaction to control the pH of the reaction system to be 3.0, drying the solid obtained by solid-liquid separation at 120° C. for 150 min to obtain an iron phosphate product, and subjecting the ammonium sulfate solution obtained by solid-liquid separation to a series of crystallization treatments to obtain an ammonium sulfate product.

[0097] The iron phosphate products obtained can be used to manufacture lithium iron phosphate battery materials, catalysts and ceramics, etc.; the ammonium sulfate products obtained can be used to manufacture medicines, dry batteries, textile printing and dyeing, detergents, etc.

[0098] Example 3

[0099] This embodiment provides a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag, the method comprising the following steps:

[0100] (1) placing the laterite nickel ore hydrometallurgical slag in a drying oven and drying it at 160° C. for 1800 min, placing the dried material in a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 250 mesh, adding CaO as a phase control agent, wherein the amount of the phase control agent added is 25% by mass of the dry basis of the laterite nickel ore hydrometallurgical slag, mixing well, placing the mixture in a crucible, covering the mixture, and placing the mixture in a high-temperature box-type furnace for phase control heat treatment, setting the heating rate to 5° C. / min, the target temperature to 1400° C., and the holding time to 420 min to obtain a phase control product;

[0101] 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 1.4-5.4wt.%, MgO 1.2-5.2wt.%, Al2O3 5.9-9.9wt.%, and CaO 1.1-4.1wt.%;

[0102] (2) placing the regulated phase product of step (1) into a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 250 mesh, and uniformly mixing it with coke as a reducing agent and sodium carbonate as a flux, wherein the amount of the reducing agent added accounts for 15% by mass of the regulated phase product, and the amount of the flux added accounts for 20% by mass of the regulated phase product. The mixed fine slag powder obtained by mixing is placed in a crucible, covered, and placed in a high-temperature box furnace for reduction roasting, setting the heating rate to 5°C / min, the target temperature to 1200°C, and the holding time to 90min to obtain a reduced product;

[0103] (3) After cooling the reduction product of step (2), the reduction product is placed in a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 250 mesh, and water is added for slurry preparation. The amount of water added is twice the mass of the reduction product. The magnetic separation intensity is set to 3500 Gs, and magnetic separation is performed in a magnetic separator to obtain magnetic material and non-magnetic material. The magnetic material and non-magnetic material are filtered and dried respectively;

[0104] The non-magnetic material can be used to produce building materials and cement products after being processed by simple conventional treatment methods;

[0105] (4) adding a 200 g / L hydrochloric acid solution as an acid leaching solution and a 200 g / L hydrogen peroxide solution as an oxidant to the magnetic substance in step (3), mixing them uniformly, controlling the solid-liquid ratio to be 1:2 g / mL, the leaching temperature to be 90° C., the leaching time to be 180 min, the stirring rate to be 300 rpm, carrying out a leaching reaction, and obtaining an iron salt solution, specifically a ferric chloride solution, by solid-liquid separation;

[0106] (5) adding the iron salt solution of step (4) to a phosphoric acid aqueous solution having a mass concentration of 300 g / L as a phosphorus source precipitant to carry out a precipitation reaction, controlling the volume ratio of the two to be 1:2.0, the temperature to be 90° C., the time to be 120 min, and the stirring rate to be 300 rpm; and simultaneously adding ammonia water having a concentration of 300 g / L during the precipitation reaction to control the pH of the reaction system to be 3.5, drying the solid obtained by solid-liquid separation at 160° C. for 240 min to obtain an iron phosphate product, and subjecting the ammonium chloride solution obtained by solid-liquid separation to a series of crystallization treatments to obtain an ammonium chloride product.

[0107] The iron phosphate products obtained can be used to manufacture lithium iron phosphate battery materials, catalysts and ceramics, etc.; the ammonium chloride products obtained can be used to manufacture medicines, dry batteries, textile printing and dyeing, detergents, etc.

[0108] Comparative Example 1

[0109] This comparative example provides a method for preparing ferric phosphate from laterite nickel ore hydrometallurgical slag. Compared with Example 1, the only difference is that the phase control heat treatment is completely omitted, and the slag is directly mixed with a reducing agent and a flux for reduction roasting. The specific content is as follows:

[0110] (1') placing the laterite nickel ore hydrometallurgical slag in a drying oven and drying it at 80°C for 600min, placing the dried material in a crusher for crushing and fine grinding to obtain a fine slag powder with a target particle size of 150 mesh, and uniformly mixing it with coke as a reducing agent and sodium carbonate as a flux, wherein the amount of the reducing agent added is 5% by weight of the dry basis of the laterite nickel ore hydrometallurgical slag, and the amount of the flux added is 10% by weight of the dry basis of the laterite nickel ore hydrometallurgical slag, and the mixed fine slag powder obtained by mixing is placed in a crucible, covered, and placed in a high-temperature box furnace for reduction roasting, setting the heating rate to 1°C / min, the target temperature to 600°C, and the holding time to 30min to obtain a reduction product;

[0111] 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 1.4-5.4wt.%, MgO 1.2-5.2wt.%, Al2O3 5.9-9.9wt.%, and CaO 1.1-4.1wt.%;

[0112] (2') cooling the reduction product of step (1'), placing it in a crusher for crushing and fine grinding to obtain fine slag powder with a target particle size of 150 mesh, adding water for slurry preparation, wherein the amount of water added is 1 times the mass of the reduction product, setting the magnetic separation intensity to 1500 Gs, and magnetically separating the magnetic material and the non-magnetic material by a magnetic separator, and filtering and drying the magnetic material and the non-magnetic material respectively;

[0113] (3') adding a hydrochloric acid solution with a concentration of 80 g / L as an acid leaching solution and a hydrogen peroxide solution with a mass concentration of 60 g / L as an oxidant to the magnetic material of step (2') and mixing them uniformly, controlling the solid-liquid ratio to be 1:1 g / mL, the leaching temperature to be 60° C., the leaching time to be 30 min, and the stirring rate to be 80 rpm, to carry out a leaching reaction, and obtaining an iron salt solution, specifically a ferric chloride solution, by solid-liquid separation;

[0114] (4') adding the iron salt solution of step (3') to a phosphoric acid aqueous solution having a mass concentration of 100 g / L as a phosphorus source precipitant to carry out a precipitation reaction, controlling the volume ratio of the two to be 1:0.9, the temperature to be 60° C., the time to be 30 min, and the stirring rate to be 80 rpm; and simultaneously adding ammonia water having a concentration of 100 g / L during the precipitation reaction to control the pH of the reaction system to be 2.5, drying the solid obtained by solid-liquid separation at 80° C. for 60 min to obtain an iron phosphate product, and subjecting the ammonium chloride solution obtained by solid-liquid separation to a series of crystallization treatments to obtain an ammonium chloride product.

[0115] Compared with Comparative Example 1, in which ferric oxide in the laterite nickel ore hydrometallurgical slag is converted into ferroferric oxide only by reduction roasting, Example 1 of the present application is provided with a phase control heat treatment before reduction roasting. After the melting-solidification phase control process, part of the ferric oxide in the laterite nickel ore hydrometallurgical slag is converted into ferroferric oxide, thereby increasing the proportion of ferric oxide converted into magnetic ferroferric oxide as much as possible, so that the iron recovery rate of the subsequent magnetic separation is higher.

[0116] In summary, the method described in the present application is based on the theoretical knowledge of phase diagrams. First, the laterite nickel ore hydrometallurgical slag is evenly mixed with a phase regulator for phase regulation heat treatment, and the ferric oxide is partially converted into ferroferric oxide, which can further enrich the iron in the laterite nickel ore hydrometallurgical slag. Then, a high-purity ferroferric oxide intermediate product is obtained by reduction roasting and magnetic separation. Finally, a high-purity iron phosphate product is obtained by combining wet leaching and coprecipitation. The method described in the present application realizes the high-value utilization of iron in laterite nickel ore hydrometallurgical slag, better solves the environmental problems caused by long-term storage and landfill of laterite nickel ore hydrometallurgical slag; the prepared iron phosphate product can be used for the preparation of lithium iron phosphate batteries, and can also be used to prepare catalysts and ceramics, etc., with high economic benefits, which is conducive to promotion and application; moreover, the obtained non-magnetic material can be used to produce additional products such as building materials and cement, and the filtrate of the precipitation reaction can be used to produce ammonium chloride or ammonium sulfate products, which can be used to manufacture medicines, dry cells, textile printing and dyeing, detergents, etc., thereby further improving the maximum utilization of laterite nickel ore resources.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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 method for preparing iron phosphate from laterite nickel ore hydrometallurgical slag, comprising the following steps: (1) Mix the laterite nickel ore hydrometallurgical slag evenly with a phase regulation agent, and conduct phase regulation heat treatment to obtain a regulated phase product; (2) Crush and finely grind the regulated phase product obtained in step (1), mix it evenly with a reducing agent and a flux, and conduct reduction roasting to obtain a reduction product; (3) Crush and finely grind the reduction product obtained in step (2), add a solvent for pulp adjustment treatment, and conduct magnetic separation to obtain magnetic substances and non-magnetic substances; (4) Mix the magnetic substances obtained in step (3) evenly with an acid leaching solution and an oxidant, conduct leaching reaction, and obtain an iron salt solution through solid-liquid separation; (5) Add a phosphorus source precipitant to the iron salt solution obtained in step (4), conduct precipitation reaction, and obtain an iron phosphate product through solid-liquid separation.

2. The 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 limonitic laterite nickel ore hydrometallurgical slag; Optionally, the dry basis composition of the laterite nickel ore hydrometallurgical slag in step (1) satisfies: TFe 46 - 58wt.%, SiO2 1.4 - 5.4wt.%, MgO 1.2 - 5.2wt.%, Al2O3 5.9 - 9.9wt.%, CaO 1.1 - 4.1wt.%.

3. The method according to claim 1 or 2, wherein Before the mixing in step (1), the laterite nickel ore hydrometallurgical slag is dried, crushed and finely ground in sequence; Optionally, the drying temperature is 80 - 160°C and the time is 600 - 1800min; Optionally, the target particle size after crushing and fine grinding is 150 - 250 mesh; 4. The method according to any one of claims 1-3, wherein The phase regulation agent in step (1) includes any one or a combination of at least two of CaO, SiO2, Al2O3 or MgO; Optionally, the addition amount of the phase regulation agent in step (1) accounts for 10 - 25% of the dry basis of the laterite nickel ore hydrometallurgical slag by mass; 5. The method according to any one of claims 1-4, wherein, The heating rate of the phase regulation heat treatment in step (1) is 1 - 5°C / min; Optionally, the target temperature of the phase regulation heat treatment in step (1) is 600 - 1400°C; Optionally, the heat preservation time of the phase regulation heat treatment in step (1) is 180 - 420min; 6. The method according to any one of claims 1-5, wherein The target particle size after crushing and fine grinding in step (2) is 150 - 250 mesh; Optionally, the reducing agent in step (2) includes a carbonaceous reducing agent with a carbon content of 70 - 100wt.%, and the addition amount accounts for 5 - 15% of the mass of the regulated phase product; Optionally, the flux in step (2) includes sodium carbonate and / or potassium carbonate, and the addition amount accounts for 10 - 20% of the mass of the regulated phase product; Optionally, the heating rate of the reduction roasting in step (2) is 1 - 5°C / min; Optionally, the target temperature of the reduction roasting in step (2) is 600 - 1200°C; Optionally, the heat preservation time of the reduction roasting in step (2) is 30 - 90min; 7. The method according to any one of claims 1-6, wherein, The target particle size after crushing and fine grinding in step (3) is 150 - 250 mesh; Optionally, the addition amount of the solvent in the sizing treatment described in step (3) is 1-2 times the mass of the reduction product; Optionally, the solvent described in step (3) includes water; Optionally, the magnetic separation intensity of the magnetic separation in step (3) is 1500-3500 Gs; Optionally, the non-magnetic substance described in step (3) is used for the production of building materials and / or cement.

8. The method according to any one of claims 1-7, wherein, The acid leaching solution described in step (4) includes a hydrochloric acid solution or a sulfuric acid solution with a mass concentration of 80-200 g / L; Optionally, the oxidant described in step (4) includes hydrogen peroxide with a mass concentration of 60-200 g / L; Optionally, the solid-liquid ratio of the leaching reaction described in step (4) is 1:(1-2) g / mL; Optionally, the leaching temperature of the leaching reaction described in step (4) is 60-90 °C; Optionally, the leaching time of the leaching reaction described in step (4) is 30-180 min; Optionally, the stirring rate of the leaching reaction described in step (4) is 80-300 rpm.

9. The method according to any one of claims 1-8, wherein The phosphorus source precipitant described in step (5) includes an aqueous phosphoric acid solution with a mass concentration of 100-300 g / L; Optionally, the volume ratio of the iron salt solution to the phosphorus source precipitant described in step (5) is 1:(0.9-2.0); Optionally, the pH of the reaction system in the precipitation reaction described in step (5) is controlled to be 2.5-3.5; Optionally, the pH in the precipitation reaction described in step (5) is controlled by ammonia water with a mass concentration of 100-300 g / L; Optionally, the temperature of the precipitation reaction described in step (5) is 60-90 °C; Optionally, the time of the precipitation reaction described in step (5) is 30-120 min; Optionally, the stirring rate of the precipitation reaction described in step (5) is 80-300 rpm.

10. The method according to any one of claims 1-9, wherein, The solid obtained by solid-liquid separation in step (5) is dried to obtain the iron phosphate product; Optionally, the drying temperature is 80-160 °C and the time is 60-240 min; Optionally, the mother liquor obtained by solid-liquid separation in step (5) is subjected to crystallization treatment to obtain an ammonium salt product.

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