Method for extracting lithium from lithium-rich bauxite waste rock

Abstract

The invention discloses a method for extracting lithium from lithium-rich bauxite waste rocks, and belongs to the technical field of solid waste comprehensive utilization. The method for extracting the lithium from the lithium-rich bauxite waste rock comprises the following steps: adding the roasted lithium-rich bauxite waste rock into a double salt solution, stirring, leaching, and filtering to obtain a leaching solution; the lixivium is refrigerated, crystallized and filtered, and filtrate is lithium-rich lixivium; wherein the double salt solution comprises an aluminum potassium sulfate solution and / or an aluminum ammonium sulfate solution. Compared with the prior art, the method disclosed by the invention has the advantages of simple process, high lithium leaching rate, low requirement on equipment, recyclable leaching agent, low energy consumption, low extraction cost, few impurities in leachate, environmental friendliness and the like, is easy to industrially apply, and provides a new way and a new method for development and utilization of lithium-rich bauxite waste rock and clay type lithium ore resources.

Description

Technical Field

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

[0002] Bauxite waste is solid waste generated during the mining process of bauxite, and its output is very high. Generally, a certain amount of lithium oxide is associated with bauxite waste, and the associated Li2O content is usually greater than 0.05% (the boundary grade of associated Li2O is 0.05%), which has a high comprehensive utilization value. The lithium in bauxite waste is mainly found in clay minerals such as kaolinite and montmorillonite, and belongs to clay-type lithium resources. Lithium is widely used in batteries, nuclear industry, new energy vehicles, aerospace and other fields, and is an important mineral resource. At present, lithium salt production mainly relies on granite pegmatite-type lithium ore (spodumene and lithium mica) and brine-type lithium ore, but lithium ore resources are relatively scarce. If the utilization of lithium resources in bauxite waste can be realized, it can not only solve the problem of lithium ore resource shortage, but also effectively improve the comprehensive utilization level of bauxite solid waste, save land resources for solid waste storage, and 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) a method of activating the ore powder by cyclic heating, and leaching lithium using an aqueous formic acid solution and adding a surfactant. However, this method requires cyclic heating 2 to 4 times and has high energy consumption; (2) a method of leaching lithium using iron salt as an extractant after high-temperature activation of the lithium ore. However, this method consumes a large amount 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 complicated; (3) a method of leaching lithium using sodium sulfate and lithium ore after roasting. However, this method has a large solid ratio of the leachate, a low lithium concentration, and a relatively high energy consumption for lithium enrichment; (4) a method of extracting lithium by primary roasting, high-energy grinding, and secondary acidification roasting-acid leaching or water leaching. However, this method has high energy consumption for secondary roasting, and the leachate has a high content of impurity ions such as aluminum and calcium, and the impurity removal process is complicated.

[0004] In addition, there is little research on lithium extraction from bauxite waste rock. Compared with general clay-type lithium ore, bauxite waste rock has a higher alumina content. Using conventional lithium extraction technology, the alumina leaching rate is high and the subsequent solution purification is difficult. Therefore, it is urgent 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, recyclable leaching agent (double salt), low extraction cost, low content of impurities such as aluminum and iron in the leaching solution, and is environmentally friendly.

[0006] To achieve the above object, the present invention provides the following solutions:

[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] The calcined lithium-rich bauxite waste rock is added to a double salt solution (leaching agent), stirred and leached, filtered while hot, and washed with hot water to obtain a leachate;

[0009] The leachate is refrigerated and crystallized and then filtered, and the filtrate is a lithium-rich leachate;

[0010] The double salt solution includes potassium aluminum sulfate dodecahydrate solution and / or ammonium aluminum sulfate dodecahydrate solution.

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

[0012] Furthermore, the calcination temperature is 400-800° C. and the calcination time is 1-3 hours.

[0013] Furthermore, 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 hours.

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

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

[0016] Furthermore, the temperature of the refrigerated crystallization is 0-4°C and the time is 3-5 hours.

[0017] Furthermore, the method for extracting lithium from lithium-rich bauxite waste rock also includes preparing the complex salt crystals obtained by cold storage crystallization into a complex salt solution, which is further used for leaching lithium.

[0018] The white crystals precipitated during the cold storage crystallization process are potassium aluminum sulfate dodecahydrate or ammonium aluminum sulfate dodecahydrate, which can be used to further prepare complex salt solutions and be recycled.

[0019] Lithium in lithium-rich bauxite waste rock is mainly found in clay minerals. Lithium is mainly found in silicate minerals such as kaolinite, montmorillonite, and pyrophyllite in the form of interlayer adsorption. Lithium cannot be leached out by sulfuric acid or hydrochloric acid at room temperature and pressure. After calcination, the kaolinite, montmorillonite, pyrophyllite and other silicate minerals contained in lithium-rich bauxite waste rock undergo dehydration reactions, and the layered structure collapses and decomposes, exposing and releasing the lithium adsorbed between the layers. The lithium is activated and can be leached by H + 、Al 3+The ions are exchanged into the solution, and the physical phase of the bauxite waste rock does not change basically before and after roasting. It exists in a stable mineral form and will not be leached by the double salt solution.

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

[0021] (1) Compared with the prior art, 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, less impurities in the leaching solution, and environmental friendliness. It is easy to apply industrially and provides 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 lithium-rich bauxite waste rock by roasting, so that silicate minerals such as kaolinite, montmorillonite, and pyrophyllite undergo a dehydration reaction, the layered structure collapses and decomposes, and the lithium adsorbed between the layers is exposed and released. Then, the lithium in the lithium-rich bauxite waste rock after roasting and activation is leached using a double salt solution containing aluminum ions, so that the lithium in the lithium-rich bauxite waste rock enters the solution, thereby achieving efficient extraction of lithium. At the same time, after roasting, most of the aluminum, iron, calcium, magnesium and other elements exist in a stable mineral form, the double salt solution will not destroy the physical phase of the bauxite waste rock, and most of the impurity elements such as aluminum, iron, calcium, and magnesium will not be leached by the double salt solution (the leaching of impurity ions such as aluminum and iron is only about 5%), which brings great convenience to the subsequent solution purification and impurity removal.

[0023] (3) The present invention makes full use of the large difference in solubility of complex salts containing aluminum ions at different temperatures, places the leaching solution at low temperature to crystallize a large amount of complex salt crystals, and uses the complex salt crystals to prepare new complex salt solutions, thereby realizing the recycling of the leaching agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 The XRD spectrum of the lithium-rich bauxite waste rock used in the present invention;

[0026] Figure 2 The XRD pattern of the calcined material obtained after calcination at 750° C. for 1 h in Example 1 of the present invention;

[0027] Figure 3 This is a schematic diagram of the process of extracting lithium from lithium-rich bauxite waste rock according to the present invention. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only 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 associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are 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) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 80 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0039] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined material.

[0040] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex 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 and leach (stirring speed 200 r / min), and the leaching time is 5 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0041] The contents of components in the leaching solution were measured, and it was calculated that the leaching rate of lithium was 85.10%, the leaching rate of iron was 5.31%, and the leaching rate of aluminum was 5.27%.

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

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

[0044] (4) When the temperature of the leachate reaches room temperature, the leachate is placed in a refrigerator for low temperature refrigeration (4°C) for 5 hours. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is lithium-rich leachate. The schematic diagram of the process of extracting lithium 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 potassium aluminum sulfate dodecahydrate solution. The specific method is as follows:

[0048] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 80 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0049] (2) The powder is placed in a muffle furnace at 750°C and kept warm for 1 hour, then taken out to obtain a calcined material.

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

[0051] The contents of components in the leaching solution were measured, and it was calculated that the leaching rate of lithium was 85.20%, the leaching rate of iron was 5.50%, and the leaching rate of aluminum was 5.10%.

[0052] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 hours. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is potassium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0053] Example 3

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

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

[0056] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 80 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0057] (2) The powder is placed in a muffle furnace at 700° C. and calcined for 1 hour, then taken out to obtain a calcined material.

[0058] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex 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 and leach (stirring speed 200 r / min), and the leaching time is 5 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0059] The contents of components in the leaching solution were measured, and the leaching rates of lithium, iron, and aluminum were calculated to be 78.20%, 4.80%, and 5.02%.

[0060] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0061] Example 4

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

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

[0064] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 80 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0065] (2) The powder is placed in a muffle furnace at 600° C. and calcined for 1 hour, then taken out to obtain a calcined material.

[0066] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex 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 and leach (stirring speed 200 r / min), and the leaching time is 5 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0067] The contents of components in the leaching solution were measured, and the leaching rates of lithium, iron, and aluminum were calculated to be 65.80%, 4.37%, and 4.98%.

[0068] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0069] Example 5

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

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

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

[0073] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined material.

[0074] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex 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 and leach (stirring speed 200 r / min), and the leaching time is 5 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0075] The contents of components in the leaching solution were measured, and it was calculated that the leaching rate of lithium was 75.80%, the leaching rate of iron was 4.28%, and the leaching rate of aluminum was 4.87%.

[0076] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0077] Example 6

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

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

[0080] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 90 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0081] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined 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 and keep it warm, add the roasted material according to the liquid-solid ratio (5 mL:1 g), stir and leach (stirring speed 200 r / min), and the leaching time is 6 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0083] The contents of components in the leaching solution were measured, and it was calculated that the leaching rate of lithium was 85.20%, the leaching rate of iron was 5.38%, and the leaching rate of aluminum was 5.47%.

[0084] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0085] Example 7

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

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

[0088] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 90 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0089] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined material.

[0090] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex 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 and leach (stirring speed 200 r / min), and the leaching time is 3 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0091] The contents of components in the leaching solution were measured, and the leaching rates of lithium, iron, and aluminum were calculated to be 52.30%, 4.64%, and 4.83%.

[0092] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0093] Example 8

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

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

[0096] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 90 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0097] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined material.

[0098] (3) Prepare an aqueous solution of ammonium aluminum sulfate dodecahydrate (complex salt solution) with a concentration of 1 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 and leach (stirring speed 200 r / min), and the leaching time is 6 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0099] The contents of components in the leaching solution were measured, and the leaching rates of lithium, iron, and aluminum were calculated to be 57.10%, 5.12%, and 5.41%, respectively.

[0100] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0101] Example 9

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

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

[0104] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 90 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0105] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined 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 and keep it warm, add the roasted material according to the liquid-solid ratio (4 mL:1 g), stir and leach (stirring speed 200 r / min), and the leaching time is 6 hours. After the leaching is completed, filter it while hot and wash it with hot water (the hot water temperature is 80°C) to obtain a leachate and a residue.

[0107] The contents of components in the leaching solution were measured, and the leaching rates of lithium, iron, and aluminum were calculated to be 79.60%, 4.45%, and 4.69%, respectively.

[0108] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0109] Example 10

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

[0111] The proportion of lithium-rich bauxite waste rock finely ground to a particle size of ≤74μm is 90wt.%, heated to 60℃ for insulation, and the leaching time is 6h. The specific method is as follows:

[0112] (1) The lithium-rich bauxite waste rock is crushed and finely ground to a particle size of 90 wt.% of the lithium-rich bauxite waste rock ≤ 74 μm to obtain a powder.

[0113] (2) The powder is placed in a muffle furnace at 750°C and calcined for 1 hour, then taken out to obtain a calcined material.

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

[0115] The contents of components in the leaching solution were measured, and it was calculated that the leaching rate of lithium was 80.20%, the leaching rate of iron was 4.38%, and the leaching rate of aluminum was 3.47%.

[0116] (4) When the temperature of the leachate is about to reach room temperature, the leachate is placed in a refrigerator for low-temperature refrigeration (4° C.) for 5 h. After the refrigeration is completed, the solid and liquid are separated, and the obtained solid is ammonium aluminum sulfate dodecahydrate crystals (complex salt crystals), and the filtrate is a lithium-rich leachate.

[0117] Table 2 Main components of lithium-rich solution obtained in Example / (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] The Fe in Table 2 refers to Fe 2+ and Fe 3+ The total content of.

[0120] Comparative Example 1

[0121] The same as Example 1, except that the aqueous solution of ammonium aluminum sulfate dodecahydrate is replaced by an aqueous solution of aluminum sulfate 18hydrate of equal concentration.

[0122] The contents of components in the leaching solution were measured, and the leaching rate of lithium was calculated to be 80.52%, and the leaching rates of aluminum and iron were 5.23% and 4.86%, respectively.

[0123] Aluminum sulfate remains in the lithium-rich solution, no crystals are precipitated, and aluminum sulfate is difficult to reuse.

[0124] Comparative Example 2

[0125] The same as Example 1, except that the ammonium aluminum sulfate dodecahydrate aqueous solution is replaced by an aqueous solution of sodium aluminum sulfate dodecahydrate of equal concentration.

[0126] The content of components in the leaching solution was determined, and the leaching rate of lithium was calculated to be 78.56%, and the leaching rates of aluminum and iron were 4.98% and 4.56% respectively. After the leaching solution was refrigerated (4°C), sodium aluminum sulfate was still in the lithium-rich solution, no crystals were precipitated, and sodium aluminum sulfate was difficult to reuse.

[0127] Table 3 Comparative Example Main components of lithium-rich solution obtained / (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] The Fe in Table 3 refers to Fe 2+ and Fe 3+ The total content of.

[0130] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all 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: The following steps are involved: The calcined lithium-rich bauxite waste rock is added to a double salt solution, stirred and leached, and then filtered to obtain a leachate; The leachate is refrigerated and crystallized and then filtered, and the filtrate is a lithium-rich leachate; The double salt solution includes potassium aluminum sulfate solution and / or ammonium aluminum sulfate solution.

2. The method according to claim 1, characterized in that The lithium-rich bauxite waste rock with a particle size of ≤74 μm accounts for 60 to 90 wt.%.

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

4. The method according to claim 1, characterized in that: 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 hours.

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

7. The method according to claim 1, characterized in that The method also includes preparing the complex salt crystals obtained by cold storage crystallization into a complex salt solution, which is further used for leaching lithium.

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