A method for extracting lithium from lithium-rich bauxite waste rock

Abstract

The present invention discloses a method for extracting lithium from lithium-rich bauxite waste rock, belonging to the technical field of comprehensive utilization of solid waste. The method for extracting lithium from lithium-rich bauxite waste rock comprises the following steps: adding the roasted lithium-rich bauxite waste rock into a double salt solution, stirring for leaching and then filtering to obtain a leaching solution; carrying out refrigerated crystallization on the leaching solution and then filtering, and the filtrate is a lithium-rich leaching solution; wherein, the double salt solution comprises a potassium alum solution and / or an ammonium alum solution. Compared with the existing technology, the method of the present invention has the advantages of simple process, high lithium leaching rate, low requirements for equipment, recyclable leaching agent, low energy consumption, low extraction cost, few impurities in the leaching solution, environmental friendliness, etc., is easy to be industrially applied, and provides a new way and method for the development and utilization of lithium-rich bauxite waste rock and clay-type lithium ore resources.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of solid waste, and particularly to a method for extracting lithium from lithium-rich bauxite waste rock. Background Art

[0002] Bauxite waste rock is a solid waste generated during the mining process of bauxite, with a high output. Generally, a certain content of lithium oxide is associated with bauxite waste rock. Usually, the content of associated Li2O is greater than 0.05% (the boundary grade of associated Li2O is 0.05%), which has high comprehensive utilization value. The lithium in bauxite waste rock is mainly hosted in clay minerals such as kaolinite and montmorillonite, belonging to clay-type lithium resources. Lithium is widely used in fields such as batteries, the nuclear industry, new energy vehicles, and aerospace, and is an important mineral resource. At present, the production of lithium salts mainly relies on granitic pegmatite-type lithium ores (spodumene and lepidolite) and brine-type lithium ores. However, lithium ore resources are relatively scarce. If the utilization of lithium resources in bauxite waste rock can be realized, it can not only solve the problem of shortage of lithium ore resources, but also effectively improve the comprehensive utilization level of bauxite solid waste, save land resources for solid waste stacking, and can effectively improve the economic benefits of bauxite mining enterprises.

[0003] At present, the methods for extracting lithium from clay-type lithium ore resources are as follows: (1) Recycling heating to activate ore powder and using formic acid aqueous solution with the addition of surfactant to leach lithium. However, this method requires recycling heating 2 - 4 times, with high energy consumption; (2) After high-temperature activation of lithium ore, using iron salt as an extractant to leach lithium. However, this method has a large consumption of iron salt leaching agent, and the leachate contains a large amount of iron ions, and the subsequent impurity removal of the leachate is relatively complex; (3) Using sodium sulfate and lithium ore to roast and then water-leach lithium. However, this method has a large liquid-solid ratio of the leachate, low lithium concentration, and high energy consumption for lithium enrichment; (4) One-time roasting, high-energy grinding, and secondary acidification roasting - acid leaching or water leaching to extract lithium. However, this method has high energy consumption for secondary roasting, and the content of impurity ions such as aluminum and calcium in the leachate is high, and the impurity removal process is complex.

[0004] In addition, there is very little research on extracting lithium from bauxite waste rock. Compared with general clay-type lithium ore, bauxite waste rock has a relatively high alumina content. Using conventional lithium extraction technology, the alumina leaching rate is high, and the subsequent solution purification is difficult. Therefore, there is an urgent need to find a simple, efficient, and low-cost lithium extraction method. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for extracting lithium from lithium-rich bauxite waste rock to solve the problems existing in the above-mentioned prior art. The method of the present invention has simple process, high lithium leaching rate, the leaching agent (double salt) can be recycled, low extraction cost, low content of impurities such as aluminum and iron in the leachate, and is environmentally friendly.

[0006] To achieve the above purpose, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention: A method for extracting lithium from lithium-rich bauxite waste rock, comprising the following steps:

[0008] Adding the roasted lithium-rich bauxite waste rock into a double salt solution (leaching agent), stirring for leaching, filtering while it is hot, and washing with hot water to obtain a leaching solution;

[0009] Refrigerating and crystallizing the leaching solution and then filtering, and the filtrate is a lithium-rich leaching solution;

[0010] The double salt solution includes potassium alum solution and / or ammonium alum solution.

[0011] Further, the particle size ≤ The proportion of lithium-rich bauxite waste rock with a particle size of 74 μm is 60-90 wt.%.

[0012] Further, the roasting temperature is 400-800 °C and the time is 1-3 h.

[0013] Further, the concentration of the double salt solution is 0.5-2.0 mol / L; the temperature of the stirring leaching is 60-100 °C and the time is 3-8 h.

[0014] Even further, the temperature of the hot water washing is 80-100 °C.

[0015] Further, the dosage ratio of the lithium-rich bauxite waste rock to the double salt solution is 1 g: 3 mL - 1 g: 5 mL.

[0016] Further, the temperature of the refrigerating crystallization is 0-4 °C and the time is 3-5 h.

[0017] Even further, the method for extracting lithium from lithium-rich bauxite waste rock further includes preparing the double salt crystals obtained by refrigerating crystallization into a double salt solution and continuing to use it for leaching lithium.

[0018] The white crystals precipitated during the refrigerating crystallization process are potassium alum or ammonium alum, which can be used to continue preparing the double salt solution and recycled.

[0019] Lithium in the lithium-rich bauxite waste rock is mainly hosted in clay minerals, and lithium is mainly hosted in silicate minerals such as kaolinite, montmorillonite, and pyrophyllite in the form of interlayer adsorption. Sulfuric acid and hydrochloric acid cannot leach lithium under normal temperature and pressure. After the lithium-rich bauxite waste rock is roasted, the silicate minerals such as kaolinite, montmorillonite, and pyrophyllite contained in it undergo dehydration reactions, the layered structure collapses and decomposes, exposing and releasing the lithium adsorbed in the interlayer, and the lithium is activated and can be leached by H + 、Al 3+The plasma is exchanged into the solution, and the mineral phases of the bauxite waste rock before and after roasting are basically unchanged, existing in the form of stable minerals and not being leached by the double salt solution.

[0020] The present invention discloses the following technical effects:

[0021] (1) Compared with the existing technologies, the method of the present invention has the advantages of simple process, high lithium leaching rate, low equipment requirements, recyclable leaching agent, low energy consumption, low extraction cost, few impurities in the leaching solution, environmental friendliness, etc., and is easy to be industrially applied, providing a new way and method for the development and utilization of lithium-rich bauxite waste rock and clay-type lithium ore resources.

[0022] (2) The present invention first activates the lithium-rich bauxite waste rock by roasting, enabling dehydration reactions of silicate minerals such as kaolinite, montmorillonite, and pyrophyllite, causing the collapse and decomposition of the layered structure, exposing and releasing the lithium adsorbed between the layers. Then, a double salt solution containing aluminum ions is used to leach the lithium in the roasted and activated lithium-rich bauxite waste rock, allowing the lithium in the lithium-rich bauxite waste rock to enter the solution, achieving efficient extraction of lithium. At the same time, after roasting, most of the elements such as aluminum, iron, calcium, and magnesium exist in the form of stable minerals, and the double salt solution does not damage the mineral phase of the bauxite waste rock, and most of the impurity elements such as aluminum, iron, calcium, and magnesium are not leached by the double salt solution (the leaching of impurity ions such as aluminum and iron is only about 5%), bringing great convenience to the subsequent purification and impurity removal of the solution.

[0023] (3) The present invention makes full use of the characteristic that the solubility of the double salt containing aluminum ions varies greatly at different temperatures, places the leaching solution at low temperature to crystallize out a large amount of double salt crystals, and uses the double salt crystals to prepare a new double salt solution, realizing the recycling of the leaching agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the XRD pattern of the lithium-rich bauxite waste rock adopted by the present invention;

[0026] Figure 2 It is the XRD pattern of the roasted material obtained after roasting at 750 °C for 1 h in Example 1 of the present invention;

[0027] Figure 3 It is the process schematic diagram for extracting lithium from the lithium-rich bauxite waste rock of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and implementation schemes of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0031] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0032] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0033] The composition and content of the lithium-rich bauxite waste rock used in the present invention are shown in Table 1.

[0034] Table 1 Chemical composition of lithium-rich bauxite waste rock

[0035]

[0036] Example 1

[0037] A method for extracting lithium from lithium-rich bauxite waste rock:

[0038] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 80 wt.%, to obtain a powder.

[0039] (2) Place the powder in a muffle furnace at 750 °C, keep it for heat treatment for 1 h and then take it out to obtain a calcined material.

[0040] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C and keep it warm, add the calcined material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 5 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain the leaching solution and residue.

[0041] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 85.10%, the leaching rate of iron is 5.31%, and the leaching rate of aluminum is 5.27%.

[0042] Leaching rate calculation formula: P = (mi × Vi) / (Mi × Wi) × 100%

[0043] Where: mi - metal ion concentration, g / L; V - fixed volume of the leaching solution, L; Mi - weight of the calcined ore used for leaching, g; Wi - mass content of the metal in the calcined ore, %.

[0044] (4) When the temperature of the leaching solution drops to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration is completed, perform solid-liquid separation. The obtained solid is ammonium aluminum sulfate dodecahydrate crystal (double salt crystal), and the filtrate is the lithium-rich leaching solution. The process schematic diagram for lithium extraction from lithium-rich bauxite waste rock is shown in Figure 1 .

[0045] Example 2

[0046] A method for extracting lithium from lithium-rich bauxite waste rock:

[0047] The double salt solution is an aqueous solution of potassium aluminum sulfate dodecahydrate. The specific method is as follows:

[0048] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 80 wt.%, to obtain a powder.

[0049] (2) Place the powder in a muffle furnace at 750 °C, keep it warm for 1 h and then take it out to obtain the calcined material.

[0050] (3) Prepare an aqueous solution of potassium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C and keep it warm, add the calcined material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 5 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain the leaching solution and residue.

[0051] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 85.20%, the leaching rate of iron is 5.50%, and the leaching rate of aluminum is 5.10%.

[0052] (4) After the temperature of the leaching solution drops to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4°C) for 5 h. After the refrigeration ends, perform solid-liquid separation. The obtained solid is potassium alum dodecahydrate crystals (double salt crystals), and the filtrate is a lithium-rich leaching solution.

[0053] Example 3

[0054] A method for extracting lithium from lithium-rich bauxite waste rock:

[0055] The roasting temperature is 700°C. The specific method is as follows:

[0056] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 80 wt.%, obtaining a powder material.

[0057] (2) Place the powder material in a muffle furnace at 700°C, keep it for roasting for 1 h, and then take it out to obtain a roasted material.

[0058] (3) Prepare an aqueous solution of ammonium alum dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90°C and keep it warm. Add the roasted material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 5 h. After the leaching ends, filter while it is hot and wash with hot water (hot water temperature is 80°C) to obtain a leaching solution and a residue.

[0059] Measure the component content in the leaching solution, and calculate that the leaching rate of lithium is 78.20%, the leaching rate of iron is 4.80%, and the leaching rate of aluminum is 5.02%.

[0060] (4) After the temperature of the leaching solution drops to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4°C) for 5 h. After the refrigeration ends, perform solid-liquid separation. The obtained solid is ammonium alum dodecahydrate crystals (double salt crystals), and the filtrate is a lithium-rich leaching solution.

[0061] Example 4

[0062] A method for extracting lithium from lithium-rich bauxite waste rock:

[0063] The roasting temperature is 600°C. The specific method is as follows:

[0064] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 80 wt.%, obtaining a powder material.

[0065] (2) Place the powder material in a muffle furnace at 600°C, keep it for roasting for 1 h, and then take it out to obtain a roasted material.

[0066] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C and keep it warm, add the calcined material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 5 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain the leaching solution and the residue.

[0067] Measure the component content in the leaching solution, and calculate that the leaching rate of lithium is 65.80%, the leaching rate of iron is 4.37%, and the leaching rate of aluminum is 4.98%.

[0068] (4) Wait for the temperature of the leaching solution to drop to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration is completed, separate the solid and liquid. The obtained solid is ammonium aluminum sulfate dodecahydrate crystal (double salt crystal), and the filtrate is the lithium-rich leaching solution.

[0069] Example 5

[0070] A method for extracting lithium from lithium-rich bauxite waste rock:

[0071] The proportion of lithium-rich bauxite waste rock ground to a particle size ≤ 74 μm is 60%. The specific method is as follows:

[0072] (1) Crush and grind the lithium-rich bauxite waste rock to a particle size ≤ 74 μm, and the proportion of the lithium-rich bauxite waste rock is 60% to obtain a powder.

[0073] (2) Place the powder in a muffle furnace at 750 °C, keep it warm and calcine for 1 h, then take it out to obtain the calcined material.

[0074] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C and keep it warm, add the calcined material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 5 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain the leaching solution and the residue.

[0075] Measure the component content in the leaching solution, and calculate that the leaching rate of lithium is 75.80%, the leaching rate of iron is 4.28%, and the leaching rate of aluminum is 4.87%.

[0076] (4) Wait for the temperature of the leaching solution to drop to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration is completed, separate the solid and liquid. The obtained solid is ammonium aluminum sulfate dodecahydrate crystal (double salt crystal), and the filtrate is the lithium-rich leaching solution.

[0077] Example 6

[0078] A method for extracting lithium from lithium-rich bauxite waste rock:

[0079] The proportion of lithium-rich bauxite waste stone finely ground to a particle size of ≤74 μm is 90 wt.%, and the leaching time is 6 h. The specific method is as follows:

[0080] (1) Crush and finely grind the lithium-rich bauxite waste stone until the proportion of lithium-rich bauxite waste stone with a particle size of ≤74 μm is 90 wt.% to obtain a powder material.

[0081] (2) Place the powder material in a muffle furnace at 750 °C, keep it for heat preservation and roasting for 1 h, and then take it out to obtain a roasted material.

[0082] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C for heat preservation, add the roasted material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 6 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain a leaching solution and a residue.

[0083] Measure the component content in the leaching solution, and calculate that the leaching rate of lithium is 85.20%, the leaching rate of iron is 5.38%, and the leaching rate of aluminum is 5.47%.

[0084] (4) Wait for the temperature of the leaching solution to drop to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration is completed, perform solid-liquid separation. The obtained solid is ammonium aluminum sulfate dodecahydrate crystal (double salt crystal), and the filtrate is a lithium-rich leaching solution.

[0085] Example 7

[0086] A method for extracting lithium from lithium-rich bauxite waste stone:

[0087] The proportion of lithium-rich bauxite waste stone finely ground to a particle size of ≤74 μm is 90 wt.%, and the leaching time is 3 h. The specific method is as follows:

[0088] (1) Crush and finely grind the lithium-rich bauxite waste stone until the proportion of lithium-rich bauxite waste stone with a particle size of ≤74 μm is 90 wt.% to obtain a powder material.

[0089] (2) Place the powder material in a muffle furnace at 750 °C, keep it for heat preservation and roasting for 1 h, and then take it out to obtain a roasted material.

[0090] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C for heat preservation, add the roasted material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 3 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain a leaching solution and a residue.

[0091] The component contents in the leaching solution were determined, and the lithium leaching rate was calculated to be 52.30%, the iron leaching rate was 4.64%, and the aluminum leaching rate was 4.83%.

[0092] (4) After the temperature of the leaching solution dropped to room temperature, the leaching solution was placed in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration ended, solid-liquid separation was carried out. The obtained solid was ammonium aluminum sulfate dodecahydrate crystals (double salt crystals), and the filtrate was a lithium-rich leaching solution.

[0093] Example 8

[0094] A method for extracting lithium from lithium-rich bauxite waste rock:

[0095] The proportion of lithium-rich bauxite waste rock ground to a particle size ≤ 74 μm was 90 wt.%, the concentration of the ammonium aluminum sulfate dodecahydrate solution was 1 mol / L, and the leaching time was 6 h. The specific method is as follows:

[0096] (1) The lithium-rich bauxite waste rock was crushed and ground to a particle size ≤ 74 μm, and the proportion of the lithium-rich bauxite waste rock was 90 wt.%, obtaining a powder material.

[0097] (2) The powder material was placed in a muffle furnace at 750 °C, kept warm and roasted for 1 h, and then taken out to obtain a roasted material.

[0098] (3) An aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 1 mol / L was prepared, heated to 90 °C and kept warm. The roasted material was added according to the liquid-solid ratio (5 mL:1 g), and stirring leaching was carried out (stirring speed 200 r / min), and the leaching time was 6 h. After the leaching ended, hot filtration was carried out while it was hot, and hot water washing was carried out (hot water temperature was 80 °C) to obtain a leaching solution and a residue.

[0099] The component contents in the leaching solution were determined, and the lithium leaching rate was calculated to be 57.10%, the iron leaching rate was 5.12%, and the aluminum leaching rate was 5.41%.

[0100] (4) After the temperature of the leaching solution dropped to room temperature, the leaching solution was placed in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration ended, solid-liquid separation was carried out. The obtained solid was ammonium aluminum sulfate dodecahydrate crystals (double salt crystals), and the filtrate was a lithium-rich leaching solution.

[0101] Example 9

[0102] A method for extracting lithium from lithium-rich bauxite waste rock:

[0103] The proportion of lithium-rich bauxite waste rock ground to a particle size ≤ 74 μm was 90 wt.%, the roasted material was added according to the liquid-solid ratio (4 mL:1 g), and the leaching time was 6 h. The specific method is as follows:

[0104] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of the lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 90 wt.%, to obtain a powder.

[0105] (2) Place the powder in a muffle furnace at 750 °C, keep it for heat preservation and roasting for 1 h, and then take it out to obtain a roasted material.

[0106] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 90 °C for heat preservation, add the roasted material according to the liquid-solid ratio (4 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 6 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain a leaching solution and a residue.

[0107] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 79.60%, the leaching rate of iron is 4.45%, and the leaching rate of aluminum is 4.69%.

[0108] (4) Wait for the temperature of the leaching solution to drop to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration is completed, separate the solid and liquid. The obtained solid is ammonium aluminum sulfate dodecahydrate crystal (double salt crystal), and the filtrate is a lithium-rich leaching solution.

[0109] Example 10

[0110] A method for extracting lithium from lithium-rich bauxite waste rock:

[0111] Finely grind until the proportion of the lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 90 wt.%, heat it to 60 °C for heat preservation, and the leaching time is 6 h. The specific method is as follows:

[0112] (1) Crush and finely grind the lithium-rich bauxite waste rock until the proportion of the lithium-rich bauxite waste rock with a particle size ≤ 74 μm is 90 wt.%, to obtain a powder.

[0113] (2) Place the powder in a muffle furnace at 750 °C, keep it for heat preservation and roasting for 1 h, and then take it out to obtain a roasted material.

[0114] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (double salt solution) with a concentration of 2 mol / L, heat it to 60 °C for heat preservation, add the roasted material according to the liquid-solid ratio (5 mL:1 g), stir for leaching (stirring speed 200 r / min), and the leaching time is 6 h. After the leaching is completed, filter while it is hot and wash with hot water (hot water temperature is 80 °C) to obtain a leaching solution and a residue.

[0115] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 80.20%, the leaching rate of iron is 4.38%, and the leaching rate of aluminum is 3.47%.

[0116] (4) After the temperature of the leaching solution drops to room temperature, place the leaching solution in a refrigerator for low-temperature refrigeration (4 °C) for 5 h. After the refrigeration ends, perform solid-liquid separation. The obtained solid is ammonium aluminum sulfate dodecahydrate crystals (double salt crystals), and the filtrate is the lithium-rich leaching solution.

[0117] Table 2 Main components of the lithium-rich solution obtained in the examples / (mg / L)

[0118] Example <![CDATA[Li + > <![CDATA[Al 3+ > <![CDATA[Mg 2+ > <![CDATA[Ca 2+ > Fe 1 475 2105 118 296 149 2 468 2139 105 281 140 3 440 2156 98 286 136 4 363 2099 100 279 142 5 420 2115 106 280 153 6 481 2120 108 300 152 7 246 2023 94 272 131 8 320 2043 100 300 142 9 450 2089 95 271 138 10 458 2100 115 290 140

[0119] Fe in Table 2 refers to the total content of Fe 2+ and Fe 3+ in total.

[0120] Comparative Example 1

[0121] Same as Example 1, the only difference is that the ammonium aluminum sulfate dodecahydrate aqueous solution is replaced with an aluminum sulfate octadecahydrate aqueous solution of the same concentration.

[0122] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 80.52%, and the leaching rates of aluminum and iron are 5.23% and 4.86% respectively.

[0123] Aluminum sulfate is still in the lithium-rich solution, and no crystals precipitate. It is difficult to reuse aluminum sulfate.

[0124] Comparative Example 2

[0125] Same as Example 1, the only difference is that the ammonium aluminum sulfate dodecahydrate aqueous solution is replaced with a sodium aluminum sulfate dodecahydrate aqueous solution of the same concentration.

[0126] Determine the component content in the leaching solution, and calculate that the leaching rate of lithium is 78.56%, and the leaching rates of aluminum and iron are 4.98% and 4.56% respectively. After the leaching slurry is refrigerated (4 °C), sodium aluminum sulfate is still in the lithium-rich solution, and no crystals precipitate. It is difficult to reuse sodium aluminum sulfate.

[0127] Table 3 Main components of the lithium-rich solution obtained in the comparative examples / (mg / L)

[0128] Comparative Example <![CDATA[Li + > <![CDATA[Al 3+ > <![CDATA[Mg 2+ > <![CDATA[Ca 2+ > Fe 1 443 37095 125 300 153 2 439 37256 112 279 140

[0129] Fe in Table 3 refers to the total content of Fe 2+ and Fe 3+ in total.

[0130] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for extracting lithium from lithium-rich bauxite waste rock, characterized in that, It includes the following steps: Adding the roasted lithium-rich bauxite waste stone into the double salt solution, stirring for leaching and then filtering to obtain the leaching solution; Performing cold storage crystallization on the leaching solution and then filtering, and the filtrate is the lithium-rich leaching solution; The double salt solution includes potassium alum solution and / or ammonium alum solution; The temperature of the stirring leaching is 60-100°C, and the time is 3-8h.

2. The method according to claim 1, wherein The proportion of the lithium-rich bauxite waste stone with a particle size ≤ 74μm in the lithium-rich bauxite waste stone is 60-90wt.%.

3. The method according to claim 1, characterized in that, The temperature of the roasting is 400-800°C, and the time is 1-3h.

4. The method according to claim 1, characterized in that, The concentration of the double salt solution is 0.5-2.0mol / L.

5. The method according to claim 1, characterized in that The dosage ratio of the lithium-rich bauxite waste stone to the double salt solution is 1g:3mL-1g:5mL.

6. The method according to claim 1, characterized in that The temperature of the cold storage crystallization is 0-4°C, and the time is 3-5h.

7. The method according to claim 1, wherein It also includes preparing the double salt crystals obtained by cold storage crystallization into a double salt solution and continuing to use it for leaching lithium.

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