Method for extracting nickel and cobalt from laterite-nickel ore and synchronously preparing iron phosphate

Abstract

The invention provides a method for extracting nickel and cobalt from laterite-nickel ore and synchronously preparing iron phosphate. The method comprises the following steps: mixing laterite-nickel ore with a carbonate compound, and carrying out roasting treatment to obtain a roasted product; and carrying out normal-pressure acid leaching treatment on the roasted product, and carrying out solid-liquid separation to obtain iron phosphate leaching residues and nickel-cobalt-enriched leaching liquid. The method provided by the invention is simple in process and low in cost, the nickel and cobalt recovery rate is high and can reach 90% or above, the generated iron phosphate can be directly used as the leaching residue for the cathode material of the lithium iron phosphate battery, the treatment process is simplified, the influence on the environment is reduced, no waste residue is generated, and the method is suitable for industrial production. The efficient utilization of resources and the sustainable development of the environment are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of laterite nickel ore hydrometallurgy, and particularly relates to a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate. Background Art

[0002] Nickel is widely used in industry and is a key raw material in the manufacture of stainless steel, batteries, catalysts, and other products. With the continued development of clean energy, and the increasing demand for nickel in batteries as a carrier of clean energy, the International Nickel Study Group (INSG) predicts that global nickel demand will increase by 135% in 2025 compared to 2019, primarily due to the increased use of renewable energy.

[0003] Indonesia is rich in laterite nickel ore, accounting for 72% of global nickel reserves, of which 28% is associated with sulfide ores. However, current global nickel production primarily comes from sulfide ores, accounting for 55.3%, while laterite nickel ore accounts for only 44.7%. Indonesia holds 42.8% of the world's nickel reserves, primarily in the form of laterite nickel ore.

[0004] Laterite nickel ore can be divided into limonite, clay, and humus types based on their elemental content. Limonite-type ore has a nickel content of 0.8-1.5%, an iron content of 40-50%, a magnesium content of 0.5-5%, and a cobalt content of 0.1-0.2%. Clay-type ore has a nickel content of 0.6-2%, an iron content of 10-30%, a magnesium content of 5-15%, and a cobalt content of 0.02-0.1%. Humus-type ore has a nickel content of 1.5-4%, an iron content of 10-25%, a magnesium content of 10-35%, and a cobalt content of 0.02-0.1%. Due to its higher magnesium content, humus-type ore is more suitable for pyrometallurgical processes, while limonite-type ore is more suitable for hydrometallurgical processes.

[0005] Currently, the primary nickel extraction method being developed globally is hydrometallurgy, as it is cheaper and more environmentally friendly than pyrometallurgical processes. Specific hydrometallurgical methods include high-pressure acid leaching, reduction roasting-ammonia leaching, and atmospheric pressure leaching. High-pressure acid leaching is the primary technology for extracting nickel from limonitic laterite nickel ore, offering advantages such as low energy consumption, low carbon emissions, and high nickel and cobalt recoveries (>90%). However, it requires high magnesium (<5%) and aluminum content in the ore, which can easily precipitate and form scale, leading to severe equipment corrosion. Furthermore, when this method is used to treat laterite nickel ore, sulfuric acid is used to produce hematite as leaching residue, resulting in a continuous accumulation of leaching residue during the leaching process. Currently, the primary methods for treating leaching residue are deep-sea tailings landfill and stockpiling, which can lead to environmental pollution and waste of resources. Furthermore, for every ton of nickel produced, 100 tons of leaching residue are generated. The reduction roasting-ammonia leaching process can process laterite nickel ores with MgO content greater than 10%, and has the advantages of reagent recycling and low cost, but the nickel and cobalt recovery rate is low (nickel recovery rate 75-80%, cobalt recovery rate less than 50%). The atmospheric pressure leaching process has the advantages of simple process, low energy consumption, small equipment, easy operation and control, and low initial investment cost, simple and safe operation, so it has certain advantages, but there are disadvantages such as low leaching rate, difficulty in leachate separation, and high nickel content in the leached residue. In particular, in the selection of leaching agent, sulfuric acid is the most commonly used acid in hydrometallurgy, with the advantages of low acid consumption and high recovery rate (more than 90%), but it will produce hematite slag, which is usually landfilled or dumped into the sea, causing environmental pollution. For example, in patent US8361191B2, a normal pressure acid leaching process is reported. The leaching process of this patent uses sulfuric acid. Although it has certain effects, its disadvantage is that it will produce leached residue, which is usually dumped into the sea or buried, thereby causing environmental pollution. In addition, the discarded slag contains relatively high iron ore, which has certain economic value. Therefore, if it is to be used, it must be further processed to be used as cathode material for lithium iron phosphate batteries, which undoubtedly increases the complexity of the process.

[0006] Therefore, there is an urgent need to provide a simple and low-cost recovery method to improve the nickel and cobalt leaching rate while obtaining high-value-added iron phosphate. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention aims to provide a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing iron phosphate. The method provided by the present invention is not only simple and cost-effective, but also has a high nickel and cobalt recovery rate of over 90%. The resulting iron phosphate, as leached residue, can be directly used as a cathode material for lithium iron phosphate batteries. This simplifies the processing process, reduces environmental impact, and eliminates waste residue, achieving efficient resource utilization and environmental sustainability.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0010] The laterite nickel ore and the carbonate compound are mixed and roasted to obtain a roasted product.

[0011] The roasted product is subjected to acid leaching treatment at normal pressure, and after solid-liquid separation, leaching residue of iron phosphate and leaching solution enriched in nickel and cobalt are obtained.

[0012] In the method provided by the present invention, first, laterite nickel ore and carbonate compounds are mixed and roasted. On the one hand, aluminum and silicon impurities can be reduced, which helps to improve the purity of the product. At the same time, as a flux, it can lower the melting point of the roasting system, making it easier for the nickel and cobalt oxides in the laterite nickel ore to react to form soluble salts, thereby improving the recovery rate of nickel and cobalt. On the other hand, the iron in the laterite nickel ore will form hematite phase iron minerals after roasting, which is conducive to subsequently separating the iron from nickel and cobalt, laying the foundation for the simultaneous preparation of iron phosphate. In addition, the CO2 gas generated by the decomposition of carbonate compounds during the roasting process can form a porous structure inside the mineral particles, increase the specific surface area of ​​the roasted product, increase porosity, and improve the subsequent leaching selectivity of nickel and cobalt.

[0013] The method provided by the present invention is not only simple in process and low in cost, but also has a high recovery rate of nickel and cobalt, which can reach more than 90%. The iron phosphate produced as leaching residue can be directly used as the cathode material of lithium iron phosphate batteries, which simplifies the treatment process, reduces the impact on the environment, and no waste residue is generated, thereby achieving efficient utilization of resources and sustainable development of the environment.

[0014] Preferably, the carbonate compound includes any one of sodium carbonate, sodium bicarbonate, calcium carbonate or magnesium carbonate, or a combination of at least two thereof.

[0015] Preferably, based on 100% by mass of the laterite nickel ore, the added amount of the carbonate compound is 2-12 wt%, for example, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt% or 12 wt%.

[0016] In the present invention, the appropriate amount of carbonate compound added can fully bind impurities such as aluminum and silicon in the laterite nickel ore, thereby reducing the impurity content in the ferric phosphate and improving its purity. It can also effectively regulate the physical composition of the mineral, thereby significantly improving the selectivity of nickel and cobalt. If the amount of carbonate compound added is too large, it may cause the roasted material to melt and agglomerate, reducing the gas-solid contact area, hindering the reaction, requiring higher temperatures or longer roasting times, and increasing energy consumption. At the same time, the agglomerated material is difficult to break, affecting the subsequent leaching efficiency.

[0017] Preferably, the calcination temperature is 200-500°C, for example, 200°C, 300°C, 400°C or 500°C, and preferably 400-500°C.

[0018] In the present invention, the appropriate roasting temperature can fully remove moisture, water vapor and volatile compounds, and remove the hydroxyl groups on the iron, so that the limonite minerals are fully converted into iron minerals in the hematite phase (α-Fe2O3), which is helpful for the subsequent preparation of iron phosphate and the improvement of nickel and cobalt leaching selectivity.

[0019] Preferably, the calcination time is 1-2 hours, for example, 1 hour or 2 hours.

[0020] In the present invention, the porosity of the roasted product is increased to within the above range, which facilitates the subsequent acid leaching process, shortens the acid leaching time and improves the leaching rate. In addition, the retention rate of impurities such as aluminum and silicon in the leached residue is improved, reducing their interference with the preparation of iron phosphate.

[0021] Preferably, the calcination process is carried out in an air atmosphere.

[0022] Preferably, the particle size D50 of the calcined product is 5-7 μm, for example, 5 μm, 6 μm, 6.245 μm or 7 μm.

[0023] Preferably, the step of atmospheric pressure acid leaching treatment comprises:

[0024] The roasted product, phosphoric acid solution, leaching aid and solvent are mixed, and then leaching is carried out under normal pressure.

[0025] During the atmospheric pressure acid leaching process, the present invention adopts phosphoric acid as a leaching agent and simultaneously adds a leaching aid, thereby greatly improving the leaching efficiency of nickel and cobalt, and can realize the preparation of ferric phosphate and the leaching of nickel and cobalt in one step, thereby simplifying the treatment process, reducing the impact on the environment, and generating no waste residue, thereby achieving efficient resource utilization and sustainable environmental development.

[0026] It should be noted that normal pressure refers to a standard atmospheric pressure, which is 101325Pa.

[0027] Preferably, the leaching aid comprises hydrochloric acid and / or sulfuric acid.

[0028] In the present invention, the combination of hydrochloric acid and phosphoric acid not only improves the recovery rate of nickel and cobalt, but also reduces the aluminum and chromium content in the leached residue. This combination can purify FePO4 into a commercial-grade product. Therefore, this combination not only improves the metal recovery efficiency but also optimizes the quality of the leached residue, making it more suitable for subsequent industrial applications.

[0029] Preferably, the solvent includes water, for example, deionized water.

[0030] Preferably, the concentration of the phosphoric acid solution is 1-10 mol / L, for example, 1 mol / L, 3 mol / L, 5 mol / L, 7 mol / L, or 9 mol / L, etc., preferably 3-5 mol / L.

[0031] Preferably, the liquid-to-solid ratio of the phosphoric acid solution and the calcined product is (6-11) mL:1 g, for example, 6 mL:1 g, 7 mL:1 g, 8 mL:1 g, 9 mL:1 g, 10 mL:1 g or 11 mL:1 g, etc., preferably 8 mL:1 g.

[0032] In the present invention, the liquid-to-solid ratio represents the ratio of the volume of the leaching agent (phosphoric acid solution) to the mass of the ore (roasted product) during the nickel laterite leaching process. A suitable ratio enhances the interaction between the leaching agent and the ore particles, helps to maintain the concentration of the leaching agent, promotes faster reaction kinetics, improves dissolution and accelerates nickel recovery. However, excessive use of leaching agents may lead to increased operating costs and environmental problems because a large amount of spent leaching agents need to be treated before disposal. On the contrary, a lower ratio may slow down the extraction of nickel because there may not be enough leaching agents to effectively dissolve the nickel, or the leaching agent may be exhausted too quickly, resulting in incomplete recovery. The preferred liquid-to-solid ratio of the present invention to the phosphoric acid solution and the roasted product is 8mL:1g, because during the leaching process, the extraction rate of nickel exceeds 86%, the extraction rate of cobalt reaches 81%, and the extraction rate of iron is lower.

[0033] Preferably, the volume ratio of the phosphoric acid solution to the leaching aid is (6-11):1, for example, it can be 6:1, 7:1, 8:1, 9:1, 10:1 or 11:1.

[0034] In the present invention, maintaining an appropriate volume ratio of the phosphoric acid solution and the leaching aid can ensure a high leaching rate of the target component while suppressing the leaching of impurity ions and improving the purity of the leachate. Preferably, the leaching temperature is 75-95°C, for example, 75°C, 80°C, 85°C, 90°C, or 95°C.

[0035] In the present invention, suitable leaching temperature contributes to temperature being a key factor in nickel laterite leaching because it directly affects the rate of chemical reaction, the solubility of nickel and the overall efficiency of the leaching process. Temperature increase accelerates the reaction rate, promotes faster dissolution of nickel, and enhances mass transfer between the ore and the leaching agent, thereby achieving faster and more effective extraction. Higher temperatures can also improve the solubility of nickel, reduce the viscosity of the leaching agent, and allow the solution to better penetrate into the ore. However, although elevated temperatures typically enhance extraction, they also increase energy costs and increase the likelihood of producing undesirable by-products (such as iron precipitates), which may require additional purification steps.

[0036] Preferably, the leaching holding time is 1-3 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0037] Preferably, the leaching process is accompanied by stirring, and the stirring rate is 300-600 rpm, for example, 300 rpm, 400 rpm, 500 rpm or 600 rpm.

[0038] Preferably, the method comprises the following steps:

[0039] (1) pre-drying the laterite nickel ore, crushing and sieving the same to obtain pre-treated laterite nickel ore; wherein the particle size D50 of the pre-treated laterite nickel ore is 7-8 μm.

[0040] (2) mixing the pretreated laterite nickel ore and a carbonate compound, and calcining the mixture in an air atmosphere at 200-500° C. for 1-2 h to obtain a calcined product having a particle size D50 of 5-7 μm; wherein the amount of the carbonate compound added is 2-12 wt % based on the mass of the laterite nickel ore as 100%.

[0041] (3) adding a phosphoric acid solution with a concentration of 1-10 mol / L, a leaching aid, and water to the calcined product, controlling the stirring rate to 300-600 rpm, and performing acid leaching treatment at 75-95° C. and normal pressure for 1-3 hours, and filtering to obtain a leached residue of iron phosphate and a leachate enriched in nickel and cobalt; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is (6-11) mL:1 g; the leaching aid includes hydrochloric acid and / or sulfuric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is (6-11):1.

[0042] (4) washing and drying the leached residue of the iron phosphate to obtain an iron phosphate product.

[0043] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) In the method provided by the present invention, first, laterite nickel ore and carbonate compounds are mixed and roasted. On the one hand, aluminum and silicon impurities can be reduced, which helps to improve the purity of the product. At the same time, as a flux, it can lower the melting point of the roasting system, making it easier for nickel and cobalt oxides in the laterite nickel ore to react to form soluble salts, thereby improving the recovery rate of nickel and cobalt. On the other hand, the iron in the laterite nickel ore will form hematite phase iron minerals after roasting, which is conducive to the subsequent separation of iron from nickel and cobalt, laying the foundation for the simultaneous preparation of iron phosphate. In addition, the CO2 gas generated by the decomposition of carbonate compounds during the roasting process can form a porous structure inside the mineral particles, increase the specific surface area of ​​the roasted product, increase the porosity, and improve the subsequent nickel and cobalt leaching selectivity.

[0046] (2) The method provided by the present invention is not only simple in process and low in cost, but also has a high recovery rate of nickel and cobalt, which can reach more than 90%. The iron phosphate produced as leaching residue can be directly used as the cathode material of lithium iron phosphate batteries, which simplifies the processing process, reduces the impact on the environment, and no waste residue is generated, thereby achieving efficient utilization of resources and sustainable development of the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a process flow chart provided for Example 1 of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] The laterite nickel ore was subjected to ICP-OES analysis, and the analysis showed that the laterite nickel ore included the components shown in Table 1 in terms of mass fraction.

[0050] Table 1

[0051]

[0052] Example 1

[0053] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing iron phosphate, and its process flow chart is as follows: Figure 1 As shown, the method includes the following steps:

[0054] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0055] (2) 30 g of pretreated laterite nickel ore and 1.5 g of sodium carbonate were mixed and calcined in air for 1 h at a temperature of 300° C., 400° C., or 500° C. to obtain a calcined product having a particle size D50 in the range of 5-7 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0056] (3) adding 61.6 mL of a 3 mol / L phosphoric acid solution, a leaching aid, and 238.4 mL of deionized water to the calcined product, controlling the stirring rate to 300 rpm, and performing acid leaching treatment at 95° C. and normal pressure for 2 h. After filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt are obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is 10 mL:1 g; the leaching aid is hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is 8:1.

[0057] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0058] The ferric phosphate product obtained in the above example and the nickel-cobalt enriched leaching solution were subjected to elemental analysis to test the leaching rate of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 2.

[0059] Table 2

[0060]

[0061] Example 2

[0062] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0063] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0064] (2) 30 g of pretreated laterite nickel ore and sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a D50 in the range of 5-7 μm; wherein, based on the mass of the laterite nickel ore as 100%, the amount of sodium carbonate added was 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt% or 12 wt%, respectively.

[0065] (3) adding 61.6 mL of a 3 mol / L phosphoric acid solution, a leaching aid, and 238.4 mL of deionized water to the calcined product, controlling the stirring rate to 300 rpm, and performing acid leaching treatment at 95° C. and normal pressure for 2 h. After filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt are obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is 10 mL:1 g; the leaching aid is sulfuric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is 8:1.

[0066] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0067] The ferric phosphate product obtained in the above example and the nickel-cobalt enriched leaching solution were subjected to elemental analysis to test the leaching rate of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 3.

[0068] Table 3

[0069]

[0070] In summary, the use of different amounts of sodium carbonate in the calcination of laterite nickel ore at 400°C and 1 h calcination time shows that the optimal addition amount of sodium carbonate is 5 wt%, at which the nickel and cobalt recoveries are as high as 89.03% and 92.55%, respectively, and the iron recovery is as low as 20.16%.

[0071] Example 3

[0072] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0073] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0074] (2) 50 g of pretreated laterite nickel ore and 2.5 g of sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a particle size D50 of 6 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0075] (3) adding a 3 mol / L phosphoric acid solution, a leaching aid, and deionized water (the total volume of the deionized water and the phosphoric acid solution is 300 mL) to the calcined product, controlling the stirring rate to 300 rpm, and performing acid leaching treatment at 95°C and normal pressure for 2 h. After filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt are obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is 6 mL:1 g, 7 mL:1 g, 8 mL:1 g, 9 mL:1 g, 10 mL:1 g, or 11 mL:1 g, respectively; the leaching aid is hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is 8:1.

[0076] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0077] The ferric phosphate product obtained in the above example and the nickel-cobalt enriched leaching solution were subjected to elemental analysis to test the leaching rate of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 4.

[0078] Table 4

[0079]

[0080] Example 4

[0081] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0082] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0083] (2) 37.5 g of pretreated laterite nickel ore and 1.875 g of sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a particle size D50 of 6 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0084] (3) 61.6 mL of phosphoric acid solution (with a concentration of 1 mol / L, 3 mol / L, 5 mol / L, 7 mol / L or 9 mol / L, etc.), a leaching aid and 238.4 mL of deionized water were added to the calcined product, the stirring rate was controlled at 300 rpm, and the acid leaching treatment was carried out at 95°C and normal pressure for 2 h. After filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt were obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product was 8 mL:1 g; the leaching aid was hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid was 8:1.

[0085] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0086] The ferric phosphate product and the nickel-cobalt enriched leaching solution obtained in the above examples were subjected to elemental analysis to test the leaching rates of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 5.

[0087] Table 5

[0088]

[0089] Example 5

[0090] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0091] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0092] (2) 37.5 g of pretreated laterite nickel ore and 1.875 g of sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a particle size D50 of 6 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0093] (3) adding 61.6 mL of a 3 mol / L phosphoric acid solution, a leaching aid, and 238.4 mL of deionized water to the calcined product, controlling the stirring rate to 300 rpm, and performing acid leaching at 95° C. and normal pressure for 1 h, 1.5 h, 2 h, 2.5 h, or 3 h, respectively. After filtering using a filtering device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt were obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product was 8 mL:1 g; the leaching aid was hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid was 8:1.

[0094] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0095] The ferric phosphate product and the nickel-cobalt enriched leaching solution obtained in the above examples were subjected to elemental analysis to test the leaching rates of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 6.

[0096] Table 6

[0097]

[0098] Example 6

[0099] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0100] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0101] (2) 37.5 g of pretreated laterite nickel ore and 1.875 g of sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a particle size D50 of 6 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0102] (3) adding 61.6 mL of a 3 mol / L phosphoric acid solution, a leaching aid, and 238.4 mL of deionized water to the calcined product, controlling the stirring rate to 300 rpm, and performing acid leaching treatment for 3 h at 75°C, 80°C, 85°C, 90°C, or 95°C and maintaining normal pressure, and filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump to obtain a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is 8 mL:1 g; the leaching aid is hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is 8:1.

[0103] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0104] The ferric phosphate product obtained in the above example and the nickel-cobalt enriched leaching solution were subjected to elemental analysis to test the leaching rate of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 7.

[0105] Table 7

[0106]

[0107] Example 7

[0108] This embodiment provides a method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing ferric phosphate, the method comprising the following steps:

[0109] (1) The above-mentioned laterite nickel ore was pre-dried at 100° C., then ground and crushed using a rotary mill, and sieved using a 200-mesh sieve to obtain pre-treated laterite nickel ore with a particle size D50 of 7.5 μm.

[0110] (2) 37.5 g of pretreated laterite nickel ore and 1.875 g of sodium carbonate were mixed and calcined in an air atmosphere at 400° C. for 1 h to obtain a calcined product with a particle size D50 of 6 μm; wherein the amount of sodium carbonate added was 5 wt % based on the mass of the laterite nickel ore as 100%.

[0111] (3) adding 61.6 mL of a 3 mol / L phosphoric acid solution, a leaching aid, and 238.4 mL of deionized water to the calcined product, controlling the stirring rate to be 300 rpm, 400 rpm, 500 rpm, or 600 rpm, respectively, and performing acid leaching treatment at 95° C. and normal pressure for 3 h. After filtering using a filtration device consisting of a Boucher funnel (coated with two layers of filter paper) and a water vacuum pump, a leaching residue of iron phosphate and a leaching solution enriched in nickel and cobalt are obtained; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is 8 mL:1 g; the leaching aid is hydrochloric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is 8:1.

[0112] (4) The leached residue of the iron phosphate was washed three times with deionized water, each time using 200 mL of water. After washing, the residue was dried at 100° C. for 8 h to obtain an iron phosphate product.

[0113] The ferric phosphate product obtained in the above example and the nickel-cobalt enriched leaching solution were subjected to elemental analysis to test the leaching rate of the main elements in the laterite nickel ore by ICP-OES analysis, as shown in Table 8.

[0114] Table 8

[0115]

[0116] In summary, the optimal parameters include: roasting temperature of 400°C, time of 1 hour, sodium carbonate addition of 5wt%, phosphoric acid solution concentration of 3mol / L, acid leaching time of 3 hours, stirring rate of 400rpm during acid leaching, acid leaching temperature of 95°C, and liquid-solid ratio of phosphoric acid solution to roasted product of 8mL:1g. Based on these parameters, the optimal composition of the nickel-cobalt enriched leachate can be obtained as follows:

[0117] Table 9

[0118]

[0119] According to these parameters, it can also be concluded that the leached residue is the raw material of iron phosphate as the positive electrode material of lithium iron phosphate battery, and its composition is shown in Table 10:

[0120] Table 10

[0121]

[0122] Therefore, the method provided by the present invention is not only simple in process and low in cost, but also has a high recovery rate of nickel and cobalt, which can reach more than 90%. The iron phosphate produced can be directly used as leaching residue as the cathode material of lithium iron phosphate batteries, which simplifies the treatment process, reduces the impact on the environment, and no waste residue is generated, thereby achieving efficient utilization of resources and sustainable development of the environment.

[0123] It should be noted that while the present invention illustrates the process method through the above-described embodiments, the present invention is not limited to the above-described process steps, and does not necessarily rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for extracting nickel and cobalt from laterite nickel ore and simultaneously preparing iron phosphate, characterized in that: The method comprises the following steps: mixing the laterite nickel ore and the carbonate compound, and performing a roasting treatment to obtain a roasted product; The roasted product is subjected to acid leaching treatment at normal pressure, and after solid-liquid separation, leaching residue of iron phosphate and leaching solution enriched in nickel and cobalt are obtained.

2. The method according to claim 1, characterized in that The carbonate compound includes any one of sodium carbonate, sodium bicarbonate, calcium carbonate or magnesium carbonate, or a combination of at least two thereof.

3. The method according to claim 1 or 2, characterized in that Based on the mass of the laterite nickel ore being 100%, the added amount of the carbonate compound is 2-12 wt%.

4. The method according to any one of claims 1 to 3, characterized in that The calcination temperature is 200-500°C, preferably 400-500°C; Preferably, the calcination time is 1-2 hours; Preferably, the calcination process is carried out in an air atmosphere.

5. The method according to any one of claims 1 to 4, characterized in that The particle size D50 of the calcined product is 5-7 μm.

6. The method according to any one of claims 1 to 5, characterized in that The steps of the atmospheric pressure acid leaching treatment include: The roasted product, phosphoric acid solution, leaching aid and solvent are mixed, and then leaching is carried out under normal pressure; Preferably, the leaching aid comprises hydrochloric acid and / or sulfuric acid; Preferably, the solvent comprises water.

7. The method according to claim 6, characterized in that The concentration of the phosphoric acid solution is 1-10 mol / L, preferably 3-5 mol / L; Preferably, the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is (6-11) mL:1 g.

8. The method according to claim 6 or 7, characterized in that The volume ratio of the phosphoric acid solution to the leaching aid is (6-11):

1.

9. The method according to any one of claims 6 to 8, characterized in that: The leaching temperature is 75-95°C; Preferably, the leaching holding time is 1-3h; Preferably, the leaching process is accompanied by stirring, and the stirring rate is 300-600 rpm.

10. The method according to any one of claims 1 to 9, characterized in that The method comprises the following steps: (1) pre-drying the laterite nickel ore, and then crushing and sieving it to obtain pre-treated laterite nickel ore; wherein the particle size D50 of the pre-treated laterite nickel ore is 7-8 μm; (2) mixing the pretreated laterite nickel ore and a carbonate compound, and calcining the mixture in an air atmosphere at 200-500° C. for 1-2 hours to obtain a calcined product having a particle size D50 of 5-7 μm; wherein the amount of the carbonate compound added is 2-12 wt % based on the mass of the laterite nickel ore as 100%; (3) adding a phosphoric acid solution having a concentration of 1-10 mol / L, a leaching aid, and water to the calcined product, controlling the stirring rate to be 300-600 rpm, and performing acid leaching treatment at 75-95° C. and normal pressure for 1-3 hours, and filtering to obtain a leached residue of iron phosphate and a leachate enriched in nickel and cobalt; wherein the liquid-to-solid ratio of the phosphoric acid solution to the calcined product is (6-11) mL:1 g; the leaching aid includes hydrochloric acid and / or sulfuric acid; and the volume ratio of the phosphoric acid solution to the leaching aid is (6-11):1; (4) washing and drying the leached residue of the iron phosphate to obtain an iron phosphate product.

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