Method for comprehensive utilization of low-grade bauxite containing lithium

Abstract

The application relates to the technical field of comprehensive utilization of non-ferrous resources, in particular to a method for comprehensively utilizing low-grade bauxite containing lithium; the method comprises the following steps: crushing the low-grade bauxite containing lithium, then pre-selecting and grading, so as to obtain coarse-grained material and fine-grained material; first grinding the coarse-grained material, then first reselecting, so as to obtain coarse aluminum concentrate and first tailings; second grinding the coarse aluminum concentrate, then second reselecting, so as to obtain aluminum concentrate and second tailings; first magnetic separation of the aluminum concentrate, so as to obtain high-quality aluminum concentrate product and first iron concentrate; combining the fine-grained material, the first tailings and the second tailings, then second magnetic separation, so as to obtain lithium-rich concentrate and second iron concentrate; combining the first iron concentrate and the second iron concentrate, so as to obtain iron concentrate product; lithium elements in the low-grade bauxite containing lithium mainly exist in clay minerals with a Mohs hardness of less than or equal to 2.5; the method can fully recover and utilize valuable components in the low-grade bauxite containing lithium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of non-ferrous resources, and particularly relates to a method for comprehensively utilizing low-grade bauxite containing lithium. BACKGROUND

[0002] Lithium is known as "21st century energy metal" and "white oil" due to its unique properties and uses. Lithium has important strategic significance for the national economy and national defense and military industry construction, and has been listed as a strategic mineral resource by most countries and regions.

[0003] Bauxite, as the only raw material for industrial production of alumina, is formed in a tropical to subtropical climate. It is a product of enrichment after in-situ or migration of aluminum-containing rocks under strong weathering. The ore-forming process is a process in which non-ore-forming elements are continuously activated and migrated out of the system, resulting in the enrichment of ore-forming elements. In addition to typical chemical elements such as aluminum, silicon and iron, bauxite usually enriches some valuable metal elements such as lithium, vanadium, potassium, gallium, scandium, titanium, niobium and tantalum, which are crucial to modern industry. This makes bauxite gradually become an important source of these key metal mineral resources. Therefore, the rational development and utilization of low-grade bauxite resources containing lithium are of great significance to the sustainable supply of bauxite resources and the development of alumina industry. At the same time, the recovery and utilization of lithium in bauxite are also crucial to the healthy and green development of domestic lithium industry.

[0004] Currently, the associated lithium in bauxite (rock) is a new type of sedimentary lithium mineral resource. When bauxite is treated by alkali method for alumina production, the associated lithium will enter the red mud and aluminate solution. Therefore, it is of great significance to recover and utilize this part of lithium resources, in addition to lithium spodumene, lepidolite and salt lake brine, including bauxite associated lithium resources, lithium-rich clay minerals and waste lithium batteries, etc.

[0005] However, the current recovery and utilization of lithium resources in lithium-containing bauxite generally adopts acid leaching to recover lithium or a combination of flotation recovery and acid leaching. However, due to the difficulty of direct leaching of lithium, there are low lithium recovery rate, high direct leaching cost, environmental pollution caused by chemical reagents in the flotation process, and high impurity content of leaching solution, which makes it difficult to be comprehensively utilized. SUMMARY

[0006] The present application provides a method for comprehensively utilizing low-grade bauxite containing lithium to solve the technical problems of low lithium recovery rate, high direct leaching cost, environmental pollution caused by chemical reagents in the flotation process, and high impurity content of leaching solution in the existing acid leaching or combination of flotation recovery and acid leaching.

[0007] In a first aspect, the present application provides a method for comprehensively utilizing low-grade bauxite containing lithium, which comprises:

[0008] The lithium-containing medium-low grade bauxite is crushed, and then pre-classified to obtain coarse material and fine material;

[0009] The coarse material is first ground, and then first reselected to obtain coarse aluminum concentrate and first tailings;

[0010] The coarse aluminum concentrate is second ground, and then second reselected to obtain aluminum concentrate and second tailings;

[0011] The aluminum concentrate is first magnetically selected to obtain high-quality aluminum concentrate product and first iron concentrate;

[0012] The fine material, the first tailings and the second tailings are combined, and then second magnetically selected to obtain lithium-rich concentrate and second iron concentrate;

[0013] The first iron concentrate and the second iron concentrate are combined to obtain iron concentrate product;

[0014] In the lithium-containing medium-low grade bauxite, more than 80% of lithium elements by mass are present in clay minerals with Mohs hardness ≤2.5.

[0015] Optionally, the particle size of the pre-classification is 0.023mm-0.038mm.

[0016] Optionally, the crushing particle size of the crushing is ≤6mm.

[0017] Optionally, the grinding fineness of the first grinding satisfies that the content of-0.074mm material is 40%-60%.

[0018] Optionally, the grinding fineness of the second grinding satisfies that the content of-0.074mm material is 61%-85%.

[0019] Optionally, the first reselection treatment includes at least one of spiral classification reselection, spiral chute reselection and cyclone reselection.

[0020] Optionally, the second reselection treatment includes at least one of shaking table reselection, centrifugal reselection and high-frequency vibration screen reselection.

[0021] Optionally, the magnetic field strength of the first magnetic selection is 1.1T-1.5T, the diameter of the magnetic medium used in the first magnetic selection is 1mm-2mm, and the pulsating water flushing frequency of the first magnetic selection is 180 times / min-270 times / min.

[0022] Optionally, the magnetic field strength of the second magnetic separator is 0.9T to 1.3T, the diameter of the magnetic focusing medium used in the second magnetic separator is 0.5mm to 1mm, and the pulsating water jet frequency of the second magnetic separator is 140 times / min to 220 times / min.

[0023] Optionally, the chemical composition of the lithium-containing low-grade bauxite meets the following requirements: Al2O3≥45%, Fe2O3≥18%, Li2O≥0.06%, and aluminum-silicon ratio≤5; more than 85% of the aluminum minerals in the lithium-containing low-grade bauxite mainly exist in the form of gibbsite monohydrate.

[0024] The technical solutions provided in this application have the following advantages compared with the prior art:

[0025] This application provides a method for the comprehensive utilization of lithium-bearing low-grade bauxite. By defining the specific Mohs hardness of the clay minerals containing lithium in the lithium-bearing low-grade bauxite, the difference in Mohs hardness between the lithium-bearing clay minerals and the aluminum-bearing minerals can be clearly identified. Utilizing this difference, combined with staged grinding of the first and second grinding processes and staged gravity separation of the first and second gravity separation processes, the aluminum-bearing and lithium-bearing minerals in the lithium-bearing low-grade bauxite can be separated. Finally, the aluminum-bearing minerals and iron-bearing minerals in the tailings can be completely removed through the first and second magnetic separation processes, thereby obtaining high-quality aluminum concentrate, lithium-rich concentrate, and iron concentrate. Since this method adopts a physical approach and does not produce polluting products, it can effectively improve the lithium recovery rate in lithium-bearing low-grade bauxite. At the same time, the obtained high-quality aluminum concentrate, iron concentrate, and lithium-rich concentrate do not contain chemical reagents and do not affect subsequent production and use, thus realizing the comprehensive recovery and utilization of valuable components in lithium-bearing low-grade bauxite. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a method for comprehensively utilizing lithium-containing low- and medium-grade bauxite is provided for embodiments of this application.

[0029] Figure 2This is a schematic diagram of the actual process of a method for comprehensively utilizing lithium-containing low-grade bauxite, provided in an embodiment of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] The creative thinking behind this application is:

[0033] Current methods for recovering lithium resources from lithium-bearing bauxite include:

[0034] (1) Comprehensive recovery and utilization of sedimentary lithium resources. Sedimentary lithium ore is crushed and ground to obtain fine-grained minerals; the fine-grained minerals are floated to obtain flotation concentrate and flotation tailings. The flotation concentrate is a lithium-rich product, and the flotation tailings are a bauxite concentrate product; the lithium-rich product is subjected to sulfuric acid ripening and water leaching to transfer lithium from the solid phase to the liquid phase, resulting in a lithium-containing leachate; the leachate is purified to remove impurities, resulting in a final purified liquid; sodium carbonate is added to the final purified liquid for reaction, and after the reaction is complete, a precipitate is precipitated. The precipitate is washed and dried to obtain lithium carbonate; however, this method using flotation technology has problems such as difficulty in recycling water, high flotation cost, environmental pollution, and residual flotation reagents of lithium-rich products affecting subsequent acid leaching.

[0035] (2) Method for extracting lithium resources from clay-type lithium ore. First, the clay-type lithium ore is crushed and ball-milled in sequence to obtain ore powder; then, the ore powder is mixed with concentrated sulfuric acid at a temperature of 250℃~300℃ and stirred for 13h to obtain a lithium sulfate mixture; this process uses concentrated sulfuric acid for direct leaching, which has problems such as high acid consumption and high content of impurity elements in the leaching solution.

[0036] like Figure 1 As shown in the embodiments of this application, a method for the comprehensive utilization of lithium-containing low- and medium-grade bauxite is provided, the method comprising:

[0037] S1. Crushing lithium-containing low-grade bauxite, followed by pre-selection and classification to obtain coarse and fine materials respectively.

[0038] S2. The coarse material is subjected to a first grinding process, followed by a first gravity separation process to obtain crude aluminum concentrate and first tailings, respectively.

[0039] S3. The crude aluminum concentrate is subjected to a second grinding process, followed by a second gravity separation process, to obtain aluminum concentrate and second tailings, respectively.

[0040] S4. Perform a first magnetic separation on the aluminum concentrate to obtain a high-quality aluminum concentrate product and a first iron concentrate;

[0041] S5. Combine the fine-grained material, the first tailings and the second tailings, and then perform a second magnetic separation to obtain lithium-rich concentrate and second iron concentrate, respectively.

[0042] S6. Combine the first iron concentrate and the second iron concentrate to obtain the iron concentrate product;

[0043] In this case, more than 80% of the lithium element by mass in the lithium-containing low-grade bauxite is attached to clay minerals with a Mohs hardness of ≤2.5.

[0044] In this embodiment, the lithium-bearing clay minerals are refined to have a Mohs hardness below 2.5, while the Mohs hardness of aluminum-bearing minerals is generally above 6.5. Therefore, the Mohs hardness of lithium-bearing clay minerals and aluminum-bearing minerals in low-grade lithium-bearing bauxite can be effectively distinguished. The difference in Mohs hardness between lithium-bearing clay minerals and aluminum-bearing minerals can then be utilized in conjunction with subsequent two-stage grinding and two-stage gravity separation processes to achieve the separation of aluminum-bearing minerals from lithium-bearing minerals. After further two-stage magnetic separation processes, iron concentrate can be screened out, and high-quality aluminum concentrate and lithium-rich concentrate can also be obtained, thereby achieving comprehensive utilization of low-grade lithium-bearing bauxite.

[0045] It should be noted that the lithium-containing clay mineral can be chlorite, kaolinite, or illite.

[0046] In some alternative embodiments, the pre-selected particle size is 0.023 mm to 0.038 mm.

[0047] In this embodiment of the application, by controlling the specific particle size of the pre-selection and grading, smaller lithium-containing clay minerals can be separated. Therefore, the clay minerals and aluminum minerals in lithium-containing bauxite can be initially separated by pre-selection and grading, which facilitates subsequent stage grinding and stage re-selection processes.

[0048] The particle size can be 0.023mm, 0.026mm, 0.029mm, 0.032mm, 0.035mm, or 0.038mm.

[0049] In some alternative implementations, the crushed particle size is ≤6mm.

[0050] In this embodiment, controlling the specific particle size of the crushing process enables the initial separation of lithium-bearing minerals and aluminum-bearing minerals in low-grade lithium-bearing bauxite. It also facilitates the formation of crushed materials of different particle sizes between lithium-bearing clay minerals and aluminum-bearing minerals due to their different Mohs hardness. These materials are then further separated through pre-selection and grading, which facilitates subsequent staged grinding and staged re-selection processes.

[0051] In some alternative embodiments, the grinding fineness of the first grinding mill satisfies that the content of the material with a grinding fineness of -0.074 mm is 40% to 60%.

[0052] In this embodiment, controlling the grinding fineness of the first grinding process to have particles smaller than 0.074 mm constitutes a specific proportion of the total material. This allows for the preliminary separation of lithium-containing clay minerals and aluminum-containing minerals during the grinding process. If this content is too small, the preliminary separation of aluminum-containing minerals and lithium-containing clay minerals will be poor, resulting in the inability to obtain the first tailings. If this content is too large, the aluminum-containing minerals will be over-ground and lost in the first tailings, thereby reducing the Li2O content in the first tailings.

[0053] The content can be 40%, 45%, 50%, 55%, or 60%.

[0054] In some optional embodiments, the grinding fineness of the second grinding mill satisfies that the content of the material with a grinding fineness of -0.074 mm is 61% to 85%.

[0055] In this embodiment, by controlling the proportion of particles with a fineness of less than 0.074 mm in the first and second grinding processes, the aim is to achieve the individual dissociation of lithium-containing clay minerals and aluminum-containing minerals. If this content is too small, the second tailings cannot be obtained due to poor deep dissociation of aluminum-containing minerals and lithium-containing clay minerals. If this content is too large, the aluminum-containing minerals will be over-ground and lost in the second tailings, thereby reducing the Li2O content in the second tailings.

[0056] The content can be 61%, 63%, 65%, 67%, 69%, 71%, 73%, 75%, 77%, 79%, 81%, 83%, or 85%.

[0057] In some alternative implementations, the first reselection process includes at least one of spiral stage reselection, spiral chute reselection, and hydrocyclone reselection.

[0058] In some alternative implementations, the second reselection process includes at least one of shaking table reselection, centrifugal reselection, and high-frequency vibrating screen reselection.

[0059] In this embodiment of the application, by refining the specific types of the first and second separation processes, the Li2O content and recovery rate of the first and second tailings can be improved, thereby maximizing the recycling of aluminum-containing minerals and lithium-containing clay minerals.

[0060] In some optional embodiments, the magnetic field strength of the first magnetic separator is 1.1T to 1.5T, the diameter of the magnetic focusing medium used in the first magnetic separator is 1mm to 2mm, and the pulsating water jet frequency of the first magnetic separator is 180 times / min to 270 times / min.

[0061] In this embodiment, controlling the specific magnetic field strength of the first magnetic separator, the diameter of the magnetically focusing medium used, and the specific number of pulsed water jets can remove weakly magnetic iron minerals from the aluminum concentrate to obtain high-quality aluminum concentrate and first iron concentrate. When the magnetic field strength of the first magnetic separator is too low, it will not be able to remove weakly magnetic iron impurities from the aluminum concentrate. When the magnetic field strength of the first magnetic separator is too high, it will cause the aluminum concentrate to be mixed in the iron concentrate, thereby reducing the yield of aluminum concentrate and the grade of first iron concentrate.

[0062] If the diameter of the magnetic medium used in the first magnetic separation is too small, it will reduce the production efficiency of the equipment and the impurity removal effect of the magnetic separation. If the diameter of the magnetic medium used in the first magnetic separation is too large, it will reduce the excitation field effect and thus affect the impurity removal effect of the magnetic separation, thereby increasing the iron content in high-quality aluminum concentrate.

[0063] If the pulse water flow rate of the first magnetic separation is too small, the aluminum concentrate will not be able to disperse during the magnetic separation process, resulting in aluminum minerals being trapped in the first iron concentrate, thereby reducing the grade of the iron concentrate and the yield of the aluminum concentrate. If the pulse water flow rate of the first magnetic separation is too large, it will affect the service life of the pulse components in the magnetic separation equipment.

[0064] The magnetic field strength can be 1.1T, 1.2T, 1.3T, 1.4T, or 1.5T.

[0065] The diameter of the magnetic medium can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2.0mm.

[0066] The frequency of the pulsating water jets can be 180 times / min, 185 times / min, 190 times / min, 195 times / min, 200 times / min, 205 times / min, 210 times / min, 215 times / min, 220 times / min, 225 times / min, 230 times / min, 235 times / min, 240 times / min, 245 times / min, 250 times / min, 255 times / min, 260 times / min, 265 times / min, or even 270 times / min.

[0067] It should be noted that, in order to ensure the impurity removal effect of the first magnetic separation, the material used for the magnetic focusing medium is generally a steel rod.

[0068] In some optional embodiments, the magnetic field strength of the second magnetic separator is 0.9T to 1.3T, the diameter of the magnetic focusing medium used in the second magnetic separator is 0.5mm to 1mm, and the pulsating water jet frequency of the second magnetic separator is 140 times / min to 220 times / min.

[0069] In this embodiment, controlling the specific magnetic field strength of the second magnetic separator, the diameter of the magnetically focusing medium used, and the specific number of pulsed water jets can remove weakly magnetic iron minerals from the fine-grained particles, the first tailings, and the second tailings to obtain lithium-rich concentrate and second iron concentrate. When the magnetic field strength of the second magnetic separator is too low, it will not be able to remove weakly magnetic iron impurities from the fine-grained particles, the first tailings, and the second tailings. When the magnetic field strength of the first magnetic separator is too high, it will cause the fine-grained particles, the first tailings, and the second tailings to be mixed in the second iron concentrate, thereby reducing the yield of lithium-rich concentrate and the grade of second iron concentrate.

[0070] If the diameter of the magnetic medium used in the second magnetic separation is too small, it will reduce the production efficiency of the equipment and the impurity removal effect of the magnetic separation. If the diameter of the magnetic medium used in the second magnetic separation is too large, it will reduce the excitation field and affect the impurity removal effect of the magnetic separation, thereby increasing the iron content in high-quality aluminum concentrate.

[0071] If the pulsating water flow rate of the second magnetic separator is too small, the lithium-rich concentrate will not be able to disperse during the magnetic separation process, resulting in the lithium-rich concentrate being mixed in with the second iron concentrate, thereby reducing the grade of the iron concentrate and the yield of the lithium-rich concentrate. If the pulsating water flow rate of the second magnetic separator is too large, it will affect the service life of the pulsating components in the magnetic separation equipment.

[0072] The magnetic field strength can be 0.9T, 1.0T, 1.1T, 1.2T, or 1.3T.

[0073] The diameter of the magnetic medium can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1.0mm.

[0074] The frequency of the pulsating water jets can be 140 times / min, 145 times / min, 150 times / min, 155 times / min, 160 times / min, 165 times / min, 170 times / min, 175 times / min, 180 times / min, 185 times / min, 190 times / min, 195 times / min, 200 times / min, 215 times / min, or 220 times / min.

[0075] It should be noted that, in order to ensure the impurity removal effect of the second magnetic separation, the material used for the magnetic focusing medium is generally a steel rod.

[0076] In some optional embodiments, the chemical composition of the lithium-containing low-grade bauxite meets the following requirements: Al2O3≥45%, Fe2O3≥18%, Li2O≥0.06%, and aluminum-silicon ratio≤5; more than 85% of the aluminum minerals in the lithium-containing low-grade bauxite exist in the form of gibbsite.

[0077] In this embodiment, controlling the specific content of each element in lithium-containing low-grade bauxite can ensure that it contains sufficient lithium, aluminum, and other elements, thereby enabling the subsequent production of high-quality aluminum concentrate, iron concentrate, and lithium-rich concentrate, which can improve the feasibility and reliability of the method in this application.

[0078] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0079] Example 1

[0080] A lithium-bearing low-grade bauxite from a mining area in Mianchi County, Henan Province, was selected. The chemical composition of this lithium-bearing low-grade bauxite, by mass fraction, includes: Al₂O₃: 45.85%, SiO₂: 10.62%, Fe₂O₃: 10.62%, and Li₂O: 0.082%. The aluminum-bearing valuable mineral in this lithium-bearing low-grade bauxite is gibbsite, with an A / S (aluminum-silicon ratio) of 4.32. Li₂O is mainly found in chlorite and illite, while iron is mainly present in the form of hematite and siderite, along with other minerals such as rutile and anatase. The actual steps for the comprehensive utilization of lithium-bearing low-grade bauxite are as follows: Figure 2 As shown, the specific process is as follows:

[0081] First, a cone crusher is used to crush lithium-containing low-grade bauxite to -6mm. Then, a spiral classifier is used to pre-sort and classify the material with a preset particle size of 0.023mm to obtain coarse and fine materials.

[0082] The coarse material is ground in a ceramic ball mill to a fineness of -0.074mm and a content of 42.75% in one pass. Then it undergoes a first gravity separation (spiral classifier gravity separation) to obtain crude aluminum concentrate and the first tailings.

[0083] The crude aluminum concentrate was ground in a ceramic rod mill until the grinding fineness was -0.74 mm and the content was 66.22%. Then it was subjected to a second gravity separation (centrifugal gravity separation and fine sand shaking table gravity separation in series) to obtain aluminum concentrate and second tailings.

[0084] The aluminum concentrate is subjected to a first magnetic separation (magnetic field strength of 1.1T, magnetic medium of 1mm diameter steel rod, and pulsating water jetting of 220 times / min) to remove iron, resulting in high-quality aluminum concentrate and first iron concentrate;

[0085] After combining the fine-grained material, the first tailings and the second tailings, a second magnetic separation (magnetic field strength of 1.3T, magnetic medium of 1mm diameter steel rod, and pulsating water jetting of 210 times / min) is carried out to remove iron, resulting in lithium-rich concentrate and second concentrate.

[0086] The first iron concentrate and the second iron concentrate were combined to obtain iron concentrate; the specific indicators of high-quality aluminum concentrate, iron tailings and lithium-rich concentrate are shown in Table 1.

[0087] Table 1. Comprehensive Utilization Test Indicators of Lithium-Bearing Low-to-Medium Grade Bauxite in Mianchi Mining Area, Henan Province

[0088]

[0089] As shown in Table 1, after processing with a "pre-classification-gravity-magnetic combined stage grinding and stage separation" technique, the lithium-bearing low-grade bauxite in a certain area of ​​Mianchi, Henan Province, can yield a high-quality aluminum concentrate for alumina production with a yield of 76.25%, an Al2O3 content of 52.92%, and an A / S ratio of 7.93. It can also yield an iron concentrate for steel production with a yield of 12.45% and an Fe2O3 content of 80.77%, and a lithium-rich concentrate with a Li2O content of 0.578%. The lithium-rich concentrate has a enrichment ratio of 7.16 and a Li2O recovery rate of 80.89%.

[0090] Example 2

[0091] A lithium-bearing low-grade bauxite from a mining area in eastern Guizhou Province was selected. The chemical composition of this lithium-bearing low-grade bauxite, by mass fraction, includes: Al₂O₃: 45.22%, SiO₂: 9.12%, Fe₂O₃: 25.45%, and Li₂O: 0.176%. The aluminum-bearing valuable mineral in this lithium-bearing low-grade bauxite is gibbsite, with an A / S (aluminum-silicon ratio) of 4.96. Li₂O is mainly found in silicate clay minerals such as chlorite, illite, and kaolinite. Iron is mainly present in the form of hematite and goethite, along with other minerals such as rutile and anatase. The actual steps for the comprehensive utilization of lithium-bearing low-grade bauxite are as follows: Figure 2 As shown, the specific process is as follows:

[0092] First, a jaw crusher is used to crush lithium-containing low-grade bauxite to -5mm. Then, a spiral classifier is used to pre-sort and classify the material with a preset particle size of 0.023mm to obtain coarse and fine materials.

[0093] The coarse material was ground in a ceramic ball mill to a fineness of -0.074mm and a content of 46.81% in one pass. Then it was subjected to the first gravity separation (spiral classifier gravity separation) to obtain crude aluminum concentrate and the first tailings.

[0094] The crude aluminum concentrate is ground in a ceramic rod mill until the content of -0.74mm is 71.44%, and then subjected to a second gravity separation (a series of gravity separation between a fine sand shaking table and a high-frequency vibrating screen) to obtain aluminum concentrate and second tailings.

[0095] The aluminum concentrate is subjected to a first magnetic separation (magnetic field strength of 1.2T, magnetic medium of 2mm diameter steel rod, and pulsating water jetting of 200 times / min) to remove iron, resulting in high-quality aluminum concentrate and first iron concentrate;

[0096] After combining the fine-grained material, the first tailings and the second tailings, a second magnetic separation (magnetic field strength of 1.2T, magnetic medium of 0.5mm diameter steel rod, and pulsating water jetting of 190 times / min) is carried out to remove iron, resulting in lithium-rich concentrate and second concentrate.

[0097] The first iron concentrate and the second iron concentrate were combined to obtain iron concentrate; the specific indicators of high-quality aluminum concentrate, iron tailings and lithium-rich concentrate are shown in Table 2.

[0098] Table 2. Comprehensive Utilization Test Indicators of Lithium-Bearing Low-to-Medium Grade Bauxite in a Mining Area in Qiandong, Guizhou

[0099]

[0100] As shown in Table 2, after processing with a "pre-classification-gravity-magnetic combined stage grinding and stage separation" technique, the lithium-bearing low-grade bauxite in a certain area of ​​Qiandong, Guizhou Province, can yield a high-quality aluminum concentrate for alumina production with a yield of 77.21%, an Al2O3 content of 52.98%, and an A / S ratio of 8.27. It can also yield an iron concentrate for steel production with a yield of 12.67% and an Fe2O3 content of 84.63%, and a lithium-rich concentrate with a Li2O content of 1.548%. The lithium-rich concentrate has a richness ratio of 8.80 and a Li2O recovery rate of 89.01%.

[0101] Example 3

[0102] A lithium-bearing low-grade bauxite from a mining area in Shanxi Province was selected. The chemical composition of this lithium-bearing low-grade bauxite, by mass fraction, includes: Al₂O₃: 19.85%, SiO₂: 13.62%, Fe₂O₃: 19.53%, Li₂O: 0.550%, with an A / S ratio of 3.66. The aluminum-bearing valuable mineral in this lithium-bearing low-grade bauxite is gibbsite, while Li₂O is mainly found in chlorite, illite, and kaolinite. Iron is mainly present in the form of hematite, goethite, and siderite, along with other minerals such as rutile and anatase. The actual steps for the comprehensive utilization of lithium-bearing low-grade bauxite are as follows: Figure 2 As shown, the specific process is as follows:

[0103] First, a cone crusher is used to crush lithium-containing low-grade bauxite to -5mm. Then, a spiral classifier is used to pre-sort and classify the material with a preset particle size of 0.038mm to obtain coarse and fine materials.

[0104] When the coarse material is ground in a ceramic ball mill to a fineness of -0.074mm and a content of 55.45%, it undergoes a first gravity separation process (a spiral chute gravity separation and a hydrocyclone gravity separation in series) to obtain crude aluminum concentrate and the first tailings.

[0105] The crude aluminum concentrate was ground in a ceramic rod mill until the content of -0.74mm was 68.43%, and then subjected to a second gravity separation (centrifugal gravity separation and fine sand shaking table gravity separation in series) to obtain aluminum concentrate and second tailings.

[0106] The aluminum concentrate is subjected to a first magnetic separation (magnetic field strength of 1.4T, magnetic medium of 2mm diameter steel rod, and pulsating water jetting of 230 times / min) to remove iron, resulting in high-quality aluminum concentrate and first iron concentrate;

[0107] After combining the fine-grained material, the first tailings and the second tailings, a second magnetic separation (magnetic field strength of 1.3T, magnetic medium of 1mm diameter steel rod, and pulsating water jetting of 190 times / min) is carried out to remove iron, resulting in lithium-rich concentrate and second concentrate.

[0108] The first iron concentrate and the second iron concentrate were combined to obtain the iron concentrate; the specific indicators of the high-quality aluminum concentrate, iron tailings and lithium-rich concentrate are shown in Table 3.

[0109] Table 3. Comprehensive Utilization Test Indicators of Lithium-Bearing Low-to-Medium Grade Bauxite in a Mining Area of ​​Shanxi Province

[0110]

[0111] As shown in Table 3, after the "pre-classification-gravity-magnetic combined stage grinding and stage separation" technology, the lithium-bearing low-grade bauxite in a certain mining area of ​​Shanxi can yield a high-quality aluminum concentrate for alumina production with a yield of 78.55%, an Al2O3 content of 56.92%, and an A / S ratio of 5.86. It can also yield an iron concentrate for steel production with a yield of 12.09% and an Fe2O3 content of 83.26%, and a lithium-rich concentrate with a Li2O content of 4.072%. The lithium-rich concentrate has a richness ratio of 7.40 and a Li2O recovery rate of 89.51%.

[0112] Example 4

[0113] A lithium-bearing low-grade bauxite from a mining area in Pingguo, Guangxi Province, was selected. The chemical composition of this lithium-bearing low-grade bauxite, by mass fraction, includes: Al₂O₃: 53.02%, SiO₂: 14.33%, Fe₂O₃: 17.14%, Li₂O: 0.441%, with an A / S ratio of 3.50. The aluminum-bearing valuable mineral in this lithium-bearing low-grade bauxite is gibbsite, while Li₂O is mainly found in chlorite and kaolinite. Iron is mainly present in the form of hematite and goethite, along with other minerals such as rutile and anatase. The actual steps for the comprehensive utilization of lithium-bearing low-grade bauxite are as follows: Figure 2 As shown, the specific process is as follows:

[0114] First, a jaw crusher and a cone crusher are connected in series to crush the lithium-containing low-grade bauxite to -5mm. Then, a spiral classifier is used to pre-sort and classify the material with a preset particle size of 0.038mm to obtain coarse and fine materials.

[0115] When the coarse material is ground in a ceramic ball mill to a fineness of -0.074mm and a content of 50.33%, it undergoes a first gravity separation process (a spiral process gravity separation and a spiral classification gravity separation in series) to obtain crude aluminum concentrate and the first tailings.

[0116] The crude aluminum concentrate is ground in a ceramic rod mill until the grinding fineness is -0.74mm and the content is 70.45%. Then it is subjected to a second gravity separation (fine sand shaking table gravity separation and high frequency vibrating screen gravity separation) to obtain aluminum concentrate and second tailings.

[0117] The aluminum concentrate is subjected to a first magnetic separation (magnetic field strength of 1.5T, magnetic medium of 1mm diameter steel rod, and pulsating water jetting of 270 times / min) to remove iron, resulting in high-quality aluminum concentrate and first iron concentrate;

[0118] After combining the fine-grained material, the first tailings and the second tailings, the second magnetic separation (magnetic field strength of 1.3T, magnetic medium of 0.5mm diameter steel rod, and pulsating water jetting of 210 times / min) is carried out to remove iron, resulting in lithium-rich concentrate and second concentrate.

[0119] The first iron concentrate and the second iron concentrate were combined to obtain iron concentrate; the specific indicators of high-quality aluminum concentrate, iron tailings and lithium-rich concentrate are shown in Table 4.

[0120] Table 4. Comprehensive Utilization Test Indicators of Lithium-Bearing Low-to-Medium Grade Bauxite in a Mining Area of ​​Pingguo, Guangxi

[0121]

[0122] As shown in Table 4, after the lithium-bearing low-grade bauxite in a certain mining area of ​​Pingguo, Guangxi, is processed by the technology of "pre-classification-gravity and magnetic combined stage grinding and stage separation", high-quality aluminum concentrate for alumina production with a yield of 79.01%, Al2O3 content of 60.122% and A / S ratio of 6.01 can be obtained. Iron concentrate for steel production with a yield of 8.45% and Fe2O3 content of 83.00% can also be obtained. At the same time, lithium-rich concentrate with Li2O content of 3.172% can also be obtained. The richness ratio of the lithium-rich concentrate reaches 7.19, and the Li2O recovery rate reaches 90.20%.

[0123] Example 5

[0124] A lithium-bearing low-grade bauxite from a mining area in Xin'an County, Henan Province, was selected. The chemical composition of this lithium-bearing low-grade bauxite, by mass fraction, includes: Al₂O₃: 50.79%, SiO₂: 13.62%, Fe₂O₃: 16.77%, Li₂O: 0.562%, with an A / S ratio of 3.73. The aluminum-bearing valuable mineral in this lithium-bearing low-grade bauxite is gibbsite, while Li₂O is mainly found in chlorite and kaolinite. Iron is mainly present in the form of hematite, siderite, and goethite, along with other minerals such as rutile and anatase. The actual steps for the comprehensive utilization of lithium-bearing low-grade bauxite are as follows: Figure 2 As shown, the specific process is as follows:

[0125] First, a jaw crusher and a double roll crusher are used to crush the lithium-containing low-grade bauxite to -3mm. Then, a spiral classifier is used to pre-sort and classify the material with a preset particle size of 0.025mm to obtain coarse and fine materials.

[0126] The coarse material is ground in a ceramic ball mill to a fineness of -0.074mm and a content of 41.45% in one pass. Then it undergoes a first gravity separation (spiral chute gravity separation) to obtain crude aluminum concentrate and the first tailings.

[0127] The crude aluminum concentrate is ground in a ceramic rod mill until the content of -0.74mm is 64.67%, and then subjected to a second gravity separation (fine sand shaking table gravity separation and slime shaking table gravity separation in series) to obtain aluminum concentrate and second tailings.

[0128] The aluminum concentrate is subjected to a first magnetic separation (magnetic field strength of 1.5T, magnetic medium of 2mm diameter steel rod, and pulsating water jetting of 230 times / min) to remove iron, resulting in high-quality aluminum concentrate and first iron concentrate;

[0129] After combining the fine-grained material, the first tailings and the second tailings, the second magnetic separation (magnetic field strength of 1.2T, magnetic medium of 0.5mm diameter steel rod, and pulsating water jetting of 210 times / min) is carried out to remove iron, resulting in lithium-rich concentrate and second concentrate.

[0130] The first iron concentrate and the second iron concentrate were combined to obtain the iron concentrate; the specific indicators of high-quality aluminum concentrate, iron tailings and lithium-rich concentrate are shown in Table 5.

[0131] Table 5. Comprehensive Utilization Test Indicators of Lithium-Bearing Low-to-Medium Grade Bauxite in a Mining Area of ​​Xin'an County, Henan Province

[0132]

[0133] As shown in Table 5, after the lithium-bearing low-grade bauxite in a mining area of ​​Xin'an, Henan Province is processed by the technology of "pre-classification-gravity and magnetic combined stage grinding and stage separation", high-quality aluminum concentrate for alumina production with a yield of 76.76%, Al2O3 content of 57.93% and A / S ratio of 6.69 can be obtained. Iron concentrate for steel production with a yield of 9.26% and Fe2O3 content of 80.86% can also be obtained. At the same time, lithium-rich concentrate with Li2O content of 3.862% can also be obtained. The enrichment ratio of the lithium-rich concentrate reaches 6.52, and the Li2O recovery rate reaches 91.20%.

[0134] Comparative Example 1

[0135] Comparative Example 1 and Example 1 will be compared. The difference between Comparative Example 1 and Example 1 is as follows:

[0136] The lithium-containing low-grade bauxite in Example 1 was processed using "a comprehensive recovery and utilization method for sedimentary lithium resources" to obtain aluminum concentrate for alumina production with a yield of 80.02%, Al2O3 content of 50.81%, and A / S ratio of 6.73, as well as lithium-rich concentrate with a yield of 19.98%, Li2O content of 0.238%, and rich ore ratio of 2.90.

[0137] This indicates that the indicators of the lithium-rich concentrate obtained in Example 1 are significantly better than those in Comparative Example 1.

[0138] Comparative Example 2

[0139] Comparative Example 2 and Example 2 will be compared. The difference between Comparative Example 2 and Example 2 is as follows:

[0140] The lithium-containing low-grade bauxite in Example 2 was processed using "a comprehensive recovery and utilization method for sedimentary lithium resources" to obtain aluminum concentrate for alumina production with a yield of 79.22%, Al2O3 content of 50.11%, and A / S ratio of 6.85, as well as lithium-rich concentrate with a yield of 20.78%, Li2O content of 0.508%, and rich ore ratio of 2.88.

[0141] This indicates that the lithium-rich concentrate obtained in Example 2 has significantly better performance than that in Comparative Example 2.

[0142] Comparative Example 3

[0143] Comparative Example 3 and Example 3 will be compared. The difference between Comparative Example 3 and Example 3 is as follows:

[0144] The lithium-containing low-grade bauxite in Example 3 was processed using "a comprehensive recovery and utilization method for sedimentary lithium resources" to obtain aluminum concentrate for alumina production with a yield of 79.88%, Al2O3 content of 55.11%, and A / S ratio of 5.41, as well as lithium-rich concentrate with a yield of 20.12%, Li2O content of 1.539%, and rich ore ratio of 2.80.

[0145] This indicates that the lithium-rich concentrate obtained in Example 3 has significantly better performance than that in Comparative Example 3.

[0146] Comparative Example 4

[0147] Comparative Example 4 and Example 4 will be compared. The difference between Comparative Example 4 and Example 4 is as follows:

[0148] The lithium-containing low-grade bauxite in Example 4 was processed using "a comprehensive recovery and utilization method for sedimentary lithium resources" to obtain aluminum concentrate for alumina production with a yield of 80.22%, Al2O3 content of 59.01%, and A / S ratio of 5.48, as well as lithium-rich concentrate with a yield of 19.78%, Li2O content of 1.244%, and rich ore ratio of 2.82.

[0149] This shows that the lithium-rich concentrate obtained in Example 4 has significantly better performance than that in Comparative Example 4.

[0150] Comparative Example 5

[0151] Comparative Example 5 and Example 5 will be compared. The difference between Comparative Example 5 and Example 5 is as follows:

[0152] The lithium-containing low-grade bauxite in Example 5 was processed using "a comprehensive recovery and utilization method for sedimentary lithium resources" to obtain aluminum concentrate for alumina production with a yield of 80.17%, Al2O3 content of 54.27%, and A / S ratio of 7.93, as well as lithium-rich concentrate with a yield of 19.83%, Li2O content of 1.704%, and rich ore ratio of 2.88.

[0153] This indicates that the lithium-rich concentrate obtained in Example 5 has significantly better performance than that in Comparative Example 5.

[0154] Relevant experimental and effect data:

[0155] The product indicators obtained by the comprehensive utilization methods of lithium-containing low-grade bauxite provided in Examples 1-5 and Comparative Examples 1-5 were statistically analyzed, and the results are shown in Table 6 below.

[0156] Table 6 Results of Example and Comparative Experiments

[0157]

[0158]

[0159] According to the data in Table 6, under similar aluminum concentrate recovery rates, the quality specifications of the aluminum concentrate obtained in Examples 1-5 of this invention are all higher than those obtained in Comparative Examples 1-5. Furthermore, the quality of the lithium-rich concentrate obtained in Examples 1-5 is significantly higher than that obtained in Comparative Examples 1-5, and the impurity content of the lithium-rich concentrate obtained in Examples 1-5 is much lower than that obtained in Comparative Examples 1-5. Additionally, Examples 1-5 also yielded a considerable amount of iron concentrate (Fe2O3 content > 80%), which can be sold as a raw material for steel production. The economic value is higher. The gravity-magnetic separation combined process used in Examples 1-5 is a physical beneficiation method. The resulting products (high-quality aluminum concentrate, iron concentrate and lithium-rich concentrate) do not contain any chemical reagents, which is convenient for subsequent production. The water used can be recycled and no additional pollutants are generated. In contrast, the products (lithium-rich concentrate and aluminum concentrate) obtained in Comparative Examples 1-5 are mixed with flotation reagents, which affects subsequent production. At the same time, the flotation process used will generate environmentally polluting return water (containing flotation reagents). This return water is difficult to treat and therefore difficult to recycle.

[0160] Therefore, Examples 1-5 of this application have significant advantages over Comparative Examples 1-5 and are more suitable for the comprehensive utilization of lithium-containing low-grade bauxite.

[0161] In summary, the method for comprehensively utilizing lithium-bearing low-to-medium grade bauxite provided in this application, by controlling the specific Mohs hardness of the clay minerals containing lithium in the bauxite, and combining staged grinding with first and second grinding, as well as staged gravity separation with first and second gravity separation, can achieve the separation of aluminum-bearing and lithium-bearing minerals in the bauxite. Finally, by using first and second magnetic separation, iron-bearing minerals in the aluminum-bearing minerals can be completely removed, thereby obtaining high-quality bauxite. This method, which utilizes physical processes to extract lithium from aluminum concentrate, lithium-rich concentrate, and iron concentrate, avoids acid leaching or flotation processes, effectively improving the lithium recovery rate in low-grade lithium-bearing bauxite. It also avoids environmental pollution caused by chemical reagents and the difficulty in comprehensively utilizing the leachate. This method overcomes the challenges of low lithium content, low aluminum content, low aluminum-to-silicon ratio (A / S), difficulty in direct lithium leaching, and high direct leaching costs in low-grade lithium-bearing bauxite, enabling the full recovery and utilization of valuable components in such ore.

[0162] This method can not only obtain high-quality aluminum concentrate for alumina production, but also lithium-rich concentrate for lithium carbonate production. Meanwhile, the by-product iron concentrate can be sold as raw material for the steel industry, realizing the comprehensive utilization of lithium-containing low-grade bauxite. It has the characteristics of high recovery rate, low cost and energy consumption, high efficiency, stable process and environmental friendliness.

[0163] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0164] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to."

[0165] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this document, "and / or" describes the association between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0166] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for the comprehensive utilization of lithium-containing low- and medium-grade bauxite, characterized in that, The method includes: The lithium-containing low-grade bauxite is crushed and then pre-sorted to obtain coarse and fine materials respectively. The coarse-grained material is subjected to a first grinding process, followed by a first gravity separation process, to obtain crude aluminum concentrate and first tailings, respectively. The crude aluminum concentrate is subjected to a second grinding process, followed by a second gravity separation process, to obtain aluminum concentrate and a second tailings, respectively. The aluminum concentrate is subjected to a first magnetic separation to obtain high-quality aluminum concentrate product and a first iron concentrate, respectively. The fine-grained material, the first tailings and the second tailings are combined and then subjected to a second magnetic separation to obtain lithium-rich concentrate and second iron concentrate, respectively. The first iron concentrate and the second iron concentrate are combined to obtain the iron concentrate product; In this case, more than 80% of the lithium element by mass in the lithium-containing low-grade bauxite is present in clay minerals with a Mohs hardness of ≤2.

5.

2. The method according to claim 1, characterized in that, The particle size of the pre-selected grade is 0.023 mm to 0.038 mm.

3. The method according to claim 1, characterized in that, The crushed particle size is ≤6mm.

4. The method according to claim 1, characterized in that, The grinding fineness of the first grinding mill meets the requirement that the content of the material with a grinding fineness of -0.074 mm is 40% to 60%.

5. The method according to claim 1, characterized in that, The grinding fineness of the second grinding mill meets the requirement that the content of the material with a grinding fineness of -0.074 mm is 61% to 85%.

6. The method according to claim 1, characterized in that, The first reselection process includes at least one of spiral stage reselection, spiral chute reselection, and hydrocyclone reselection.

7. The method according to claim 1, characterized in that, The second reselection process includes at least one of shaking table reselection, centrifugal reselection, and high-frequency vibrating screen reselection.

8. The method according to claim 1, characterized in that, The magnetic field strength of the first magnetic separator is 1.1T to 1.5T, the diameter of the magnetic medium used in the first magnetic separator is 1mm to 2mm, and the pulsating water jet frequency of the first magnetic separator is 180 times / min to 270 times / min.

9. The method according to claim 1, characterized in that, The magnetic field strength of the second magnetic separator is 0.9T to 1.3T, the diameter of the magnetic medium used in the second magnetic separator is 0.5mm to 1mm, and the pulsating water jet frequency of the second magnetic separator is 140 times / min to 220 times / min.

10. The method according to claim 1, characterized in that, The chemical composition of the lithium-containing low-grade bauxite meets the following requirements: Al2O3≥45%, Fe2O3≥18%, Li2O≥0.06%, and aluminum-silicon ratio≤5; more than 85% of the aluminum minerals in the lithium-containing low-grade bauxite exist in the form of gibbsite monohydrate.

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