A method for extracting lithium from lithium-containing material

Abstract

The present invention relates to the technical field of lithium extraction from ores, and specifically to a method for extracting lithium from lithium-containing materials. The present invention mixes a lithium-containing material with more than 90wt% concentrated sulfuric acid at a mass ratio of 1:0.1-0.5, performs a first-stage roasting, and mixes the obtained first-stage roasting material with more than 90wt% concentrated sulfuric acid at a mass ratio of 1:0.1-0.5, performs a second-stage roasting, and performs water leaching on the obtained second-stage roasting material to obtain a lithium leachate. The present invention controls the mass ratio of raw materials and concentrated sulfuric acid and adopts a two-stage roasting process, and then performs water leaching, so that the lithium in the lithium-containing material can be fully extracted, the lithium leaching rate is greatly improved, and the pH of the leachate is ≥1.5, which is conducive to the subsequent purification and impurity removal of the leachate to reduce the cost of the lithium extraction process; in the two-stage roasting process, the amount of concentrated sulfuric acid is relatively small, so that the concentrated sulfuric acid will not form a paste when mixed with the lithium ore, the mixed material will not adhere to the roasting equipment and affect the roasting efficiency, and the corrosion to the roasting equipment is small.

Description

Technical Field

[0001] The invention relates to the technical field of lithium extraction from ores, and in particular to a method for extracting lithium from lithium-containing materials. Background Art

[0002] Lithium is an important rare metal raw material. With the introduction of the national new energy development plan, lithium-ion new energy has become one of the energy industries that the country focuses on supporting and developing. Extracting lithium from lithium-containing ores is an important source of lithium.

[0003] At present, the main lithium extraction processes for lithium materials are limestone roasting, sulfate method, traditional sulfuric acid method, chlorination roasting, etc. Among them, limestone roasting, chlorination roasting and traditional sulfuric acid method generally heat treat at about 800-1100℃ for 60-120min, with high energy consumption, large material flow and large equipment investment.

[0004] Chinese patent CN113293281A discloses a method for leaching lithium from lithium mica, comprising the following steps: mixing sulfuric acid and lithium mica powder in a mass ratio of 0.75 to 1.2:1 and then roasting at a temperature of 100 to 200°C to obtain a roasted material; calcining the obtained roasted material at 800 to 900°C, and leaching the obtained calcined material in water to obtain a leachate, wherein the lithium leaching rate is up to 95.7%. Chinese patent CN104876250A discloses a method for extracting lithium and removing aluminum from lithium mica by treating lithium mica with sulfuric acid, comprising the following steps: mechanical activation of lithium mica, low-temperature (200 to 300°C) treatment with dilute sulfuric acid to extract valuable metal elements, medium-temperature sintering (700 to 900°C), tail gas recovery, and room-temperature water leaching to extract alkali metal sulfate, wherein the mass ratio of dilute sulfuric acid (50 to 75 wt%) to lithium mica is 2:1, and the lithium leaching rate is up to 95.78%. However, in the above-mentioned lithium extraction process, the calcination or sintering temperature is between 700 and 900°C, which has high energy consumption and high cost. The large amount of sulfuric acid used causes sulfuric acid to form a paste when mixed with lithium ore, and the paste easily adheres to the roasting equipment, resulting in the effective space of the roasting equipment becoming smaller and smaller, and production cannot proceed normally.

[0005] Chinese patent CN109022772A discloses a method for leaching lithium mica ore by sulfuric acid aging, and the specific steps are as follows: ① grinding: grinding the lithium mica concentrate; ② mixing acid: mixing concentrated sulfuric acid into the ground lithium mica concentrate and stirring evenly, the amount of concentrated sulfuric acid added is 0.5 to 1.5 times the mass of the original ore; ③ mixing water: mixing water again and stirring quickly and evenly, the amount of water added is 0.05 to 0.5 times the mass of the original ore; ④ aging: the lithium mica ore mixed with acid and water is heat-insulated and sealed for aging; ⑤ dilution: transferring the aging material to a leaching tank, adding a leaching agent of 1 to 6 times the amount of the original ore, stirring and dissolving lithium and valuable metals such as rubidium, cesium, potassium, etc. in the lithium mica; ⑥ liquid-solid separation: after the stirring leaching is completed, liquid-solid separation is performed to obtain a leaching solution and a leaching residue, and then the leaching residue is pan-washed; its lithium leaching rate is as high as 97.2%. However, the pH of the leaching solution obtained by the prior art is less than 0.9, which is highly acidic. Subsequent lithium extraction and impurity removal requires the consumption of a large amount of alkali, resulting in high lithium extraction process costs. Moreover, the excess sulfuric acid is converted into sulfate after alkali treatment and cannot be returned to the roasting process for reuse.

[0006] Chinese patent CN114892024A discloses a method for extracting lithium from lithium-containing clay by low-temperature roasting, comprising the following steps: 98% sulfuric acid and lithium-containing clay are mixed evenly at a liquid-solid ratio of 0.5:1 to 1:2, roasted at 180 to 250°C, and the roasted product is water-leached and then filtered to obtain a lithium-containing filtrate. In the prior art, the lithium leaching rate is below 89.32%, the lithium leaching rate is low, the acidity is strong, and a large amount of alkali is consumed for subsequent lithium extraction and impurity removal, and the lithium extraction process is costly. Moreover, the excess sulfuric acid is converted into sulfate after alkali treatment and cannot be returned to the roasting process for reuse. Summary of the invention

[0007] In view of this, the object of the present invention is to provide a method for extracting lithium from lithium-containing materials. The lithium extraction method provided by the present invention has a high lithium leaching rate and weak acidity of the leaching solution, which can greatly reduce the subsequent consumption of alkali for lithium extraction and impurity removal, thereby reducing the cost of the lithium extraction process.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for extracting lithium from a lithium-containing material, comprising the following steps:

[0010] The lithium-containing material is mixed with a first concentrated sulfuric acid, and subjected to a stage of roasting to obtain a stage of roasting material and a stage of flue gas, respectively; the mass fraction of the first concentrated sulfuric acid is ≥90%, and the mass ratio of the lithium-containing material to the first concentrated sulfuric acid is 1:0.1-0.5;

[0011] The first-stage roasting material is mixed with a second concentrated sulfuric acid, and two-stage roasting is performed to obtain a second-stage roasting material and a second-stage flue gas, respectively; the mass fraction of the second concentrated sulfuric acid is ≥90%, and the mass ratio of the first-stage roasting material to the second concentrated sulfuric acid is 1:0.1-0.5;

[0012] The second-stage roasted material is water-leached to obtain a lithium leaching solution.

[0013] Preferably, the temperature of the first stage roasting is 150-250° C., and the holding time is 0.5-3 h.

[0014] Preferably, the two-stage roasting includes low-temperature roasting, heating and high-temperature roasting in sequence; the temperature of the low-temperature roasting is 150-250°C, and the insulation time is 1-3h; the heating rate of the heating is 5-10°C / min; the temperature of the high-temperature roasting is 380-550°C, and the insulation time is 1-2h.

[0015] Preferably, the mass ratio of the second-stage roasting material to the soaking water is 1:2-4.

[0016] Preferably, the water immersion temperature is 15-100° C., and the time is 0.5-2 h.

[0017] Preferably, after the first stage of roasting, the method further comprises crushing the obtained roasted solid product to a particle size of -0.074 mm with a content of ≥40wt%.

[0018] Preferably, after the second stage roasting, the obtained roasted solid product is crushed to ≤2 mm.

[0019] Preferably, the lithium-containing material comprises one or more of lithium-containing clay ore, lepidolite concentrate and spodumene concentrate high-temperature roasted pre-treated material.

[0020] Preferably, the first stage flue gas and / or the second stage flue gas are absorbed by dilute sulfuric acid to obtain a sulfuric acid solution; when the mass fraction of the sulfuric acid solution is ≥90%, it is recycled as concentrated sulfuric acid in the first stage roasting step and / or the second stage roasting step.

[0021] Preferably, the pH value of the lithium leaching solution is ≥1.5.

[0022] The present invention provides a method for extracting lithium from a lithium-containing material, comprising the following steps: mixing the lithium-containing material with a first concentrated sulfuric acid, performing a first-stage roasting, and obtaining a first-stage roasting material and a first-stage flue gas; the mass fraction of the first concentrated sulfuric acid is ≥90%, and the mass ratio of the lithium-containing material to the first concentrated sulfuric acid is 1:0.1-0.5; mixing the first-stage roasting material with a second concentrated sulfuric acid, performing a second-stage roasting, and obtaining a second-stage roasting material and a second-stage flue gas; the mass fraction of the second concentrated sulfuric acid is ≥90%, and the mass ratio of the first-stage roasting material to the second concentrated sulfuric acid is 1:0.1-0.5; and water leaching the second-stage roasting material to obtain a lithium leaching solution. The present invention controls the mass ratio of the lithium-containing material to the concentrated sulfuric acid and the mass ratio of the first-stage roasting material to the concentrated sulfuric acid to be within the range of 1:0.1-0.5 and adopts a two-stage roasting process, followed by water leaching, so that the lithium in the lithium-containing material can be fully extracted, and the lithium leaching rate of the lithium-containing material is greatly improved. Moreover, in the two-stage roasting process, the amount of concentrated sulfuric acid used is relatively small, so that the concentrated sulfuric acid will not form a paste when mixed with the lithium ore, the mixture will not adhere to the roasting equipment and affect the roasting efficiency, and the corrosion to the roasting equipment is small.

[0023] Furthermore, the pH value of the leaching solution obtained by the lithium extraction method provided by the present invention is ≥1.5, and the leaching solution is weakly acidic, which can greatly reduce the consumption of subsequent lithium extraction and impurity removal alkali, thereby reducing the cost of the lithium extraction process.

[0024] As shown in the test results of the embodiment, after the lithium extraction method provided by the present invention is used for lithium extraction, the lithium leaching rate is above 91%, the lithium leaching rate is high, and the pH value of the leaching solution is ≥1.5. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The XRD patterns of the calcined materials calcined at 110° C. for different time periods in Example 10;

[0026] Figure 2 The XRD patterns of the calcined materials calcined at 130° C. for different time periods in Example 10;

[0027] Figure 3 The XRD patterns of the calcined materials calcined at 150° C. for different time periods in Example 10;

[0028] Figure 4 The XRD patterns of the calcined materials calcined at 170° C. for different time periods in Example 10;

[0029] Figure 5 The XRD patterns of the calcined materials calcined at 190° C. for different time periods in Example 10;

[0030] Figure 6 The XRD patterns of the calcined materials calcined at 210° C. for different time periods in Example 10;

[0031] Figure 7 The XRD patterns of the calcined materials calcined at 230° C. for different time periods in Example 10;

[0032] Figure 8 This is the XRD diagram of the calcined material obtained by calcining at 250°C for different times in Example 10. DETAILED DESCRIPTION

[0033] The present invention provides a method for extracting lithium from a lithium-containing material, comprising the following steps:

[0034] The lithium-containing material is mixed with a first concentrated sulfuric acid, and subjected to a stage of roasting to obtain a stage of roasting material and a stage of flue gas, respectively; the mass fraction of the first concentrated sulfuric acid is ≥90%, and the mass ratio of the lithium-containing material to the first concentrated sulfuric acid is 1:0.1-0.5;

[0035] The first-stage roasting material is mixed with a second concentrated sulfuric acid, and two-stage roasting is performed to obtain a second-stage roasting material and a second-stage flue gas, respectively; the mass fraction of the second concentrated sulfuric acid is ≥90%, and the mass ratio of the first-stage roasting material to the second concentrated sulfuric acid is 1:0.1-0.5;

[0036] The second-stage roasted material is water-leached to obtain a lithium leaching solution.

[0037] Unless otherwise specified, the raw materials used in the present invention are all commercially available products.

[0038] The present invention mixes the lithium-containing material with the first concentrated sulfuric acid, performs a stage of roasting, and obtains a stage of roasting material and a stage of flue gas respectively. In the present invention, the lithium-containing material preferably includes one or more of lithium-containing clay ore, lithium mica concentrate and spodumene concentrate high-temperature roasting pretreatment material, and more preferably includes lithium-containing clay ore, lithium mica concentrate or spodumene concentrate high-temperature roasting pretreatment material; the -0.074mm particle size content in the lithium-containing material is preferably ≥65wt%, wherein "-" represents "≤". In the present invention, the preparation method of the pyroxene concentrate high-temperature roasting pretreatment material preferably includes the following steps: roasting the pyroxene concentrate to obtain the pyroxene concentrate high-temperature roasting pretreatment material; the roasting temperature is preferably 900-1100°C, more preferably 1000°C, and the roasting insulation time is preferably 1-3h, more preferably 2h. In the present invention, the mass fraction of the first concentrated sulfuric acid is ≥90%, preferably 90-98%, and more preferably 95-98%. In the present invention, the mass ratio of the lithium-containing material to the first concentrated sulfuric acid is 1:0.1-0.5, preferably 1:0.2-0.5, and more preferably 1:0.3-0.4. In the present invention, the temperature of the first stage of roasting is preferably 150-250°C, more preferably 180-230°C, and further preferably 200-220°C; the holding time of the first stage of roasting is preferably 0.5-3h, more preferably 1-2.5h, and further preferably 1-2h.

[0039] After the first stage of calcination, the present invention preferably further comprises crushing the obtained calcined solid product to a particle size of -0.074 mm with a content of ≥40wt%, to obtain a first stage calcined material. The present invention has no special limitation on the crushing, and the crushing method well known to those skilled in the art can be used to crush the particle size of -0.074 mm with a content of ≥40wt%, and the particle size of the first stage calcined material is more preferably a particle size of -0.074 mm with a content of ≥60wt%.

[0040] After obtaining the first-stage roasting material, the present invention mixes the first-stage roasting material with the second concentrated sulfuric acid, performs second-stage roasting, and obtains the second-stage roasting material and the second-stage flue gas respectively. In the present invention, the mass fraction of the second concentrated sulfuric acid is ≥90%, preferably 90-98%, and more preferably 95-98%. In the present invention, the mass ratio of the first-stage roasting material to the second concentrated sulfuric acid is 1:0.1-0.5, preferably 1:0.2-0.5, and more preferably 1:0.3-0.4. In the present invention, the two-stage roasting preferably includes low-temperature roasting, heating and high-temperature roasting in sequence; the temperature of the low-temperature roasting is preferably 150-250°C, more preferably 160-230°C, more preferably 180-220°C, and the holding time of the low-temperature roasting is preferably 1-3h, more preferably 1-2.5h, and more preferably 1.5-2h; the heating rate of the heating is preferably 5-10°C / min, more preferably 6-9°C / min, and more preferably 7-8°C / min; the temperature of the high-temperature roasting is preferably 380-550°C, more preferably 390-500°C, and more preferably 400-450°C, and the holding time of the high-temperature roasting is preferably 1-2h, and more preferably 1-1.5h; during the high-temperature roasting process, excess sulfuric acid is decomposed into SO 3 .

[0041] After the second stage calcination, the present invention preferably further comprises crushing the obtained calcined solid product to ≤2 mm to obtain the second stage calcined material. The present invention has no special limitation on the crushing, and the crushing method well known to those skilled in the art can be used to crush the solid product to a particle size of ≤2 mm. The particle size of the second stage calcined material is more preferably ≤1 mm.

[0042] After obtaining the first stage flue gas and the second stage flue gas, the present invention uses dilute sulfuric acid to absorb the first stage flue gas and / or the second stage flue gas to obtain a sulfuric acid solution; when the mass fraction of the sulfuric acid solution is ≥90%, it is recycled as concentrated sulfuric acid in the first stage roasting step and / or the second stage roasting step. In the present invention, the mass fraction of the sulfuric acid is preferably 90-98wt%, more preferably 95-98wt%.

[0043] After obtaining the second-stage roasting material, the present invention performs water leaching on the second-stage roasting material to obtain a lithium leaching solution. In the present invention, the mass ratio of the second-stage roasting material to the water for water leaching is preferably 1:2-4, more preferably 1:2.5-3.5, and further preferably 1:2.5-3. In the present invention, the temperature of the water leaching is preferably 15-100°C, more preferably 40-90°C, and further preferably 60-80°C; the time of the water leaching is preferably 0.5-2h, and more preferably 1-1.5h. After the water leaching, the present invention preferably further comprises solid-liquid separation of the obtained leached slurry to obtain a liquid component and a solid component respectively, and the solid component is washed with water and then dried to obtain a leached slag. The present invention has no special limitation on the solid-liquid separation, and a solid-liquid separation method well known to those skilled in the art can be used, such as filtration. In the present invention, the mass ratio of the second-stage roasting material to the water for water washing is preferably 1:0.5-1, and more preferably 1:0.8-1. In the present invention, the drying temperature is preferably 60 to 90° C., more preferably 80 to 90° C. The present invention has no particular limitation on the drying time, and the drying time may be performed until constant weight.

[0044] In the present invention, the pH value of the lithium leaching solution is preferably ≥1.5, more preferably 1.5-3, and further preferably 2-3; the lithium leaching solution obtained by the one-stage roasting process of the prior art is highly acidic, and subsequent lithium extraction and impurity removal requires a large amount of alkali, and the cost of the lithium extraction process is high. Moreover, the excess sulfuric acid is converted into sulfate after alkali treatment and cannot be returned to the roasting process for reuse. The present invention adopts a two-stage roasting process followed by water leaching, and the pH value of the obtained lithium leaching solution is higher, the amount of alkali consumed in subsequent lithium extraction and impurity removal is small, and the cost of the lithium extraction process is low.

[0045] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] (1) mixing lithium-containing clay ore powder (-0.074 mm particle size content ≥ 65 wt %) and 98 wt % concentrated sulfuric acid, and calcining at 210° C. for 1 h to obtain a calcined solid product and a stage of flue gas, respectively; cooling the calcined solid product to room temperature naturally and then dry-grinding it to a -0.074 mm particle size content of > 60 wt % to obtain a first stage of calcined material; wherein the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid is 1:0.5;

[0048] The main minerals of lithium-containing clay ore are lithium-containing minerals, quartz, illite and dickite, and also contain a small amount of pyrite, dolomite and calcite. The multi-element analysis results of lithium-containing clay ore are shown in Table 1:

[0049] Table 1 Multi-element analysis results of lithium-containing clay ore

[0050] composition <![CDATA[Li 2 The]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[TFe 2 THE 3 ]]> <![CDATA[SiO 2 ]]> <![CDATA[TiO 2 ]]> <![CDATA[P 2 THE 5 <!-- 4 --> ]]> Content / wt% 0.51 21.93 6.66 56.93 0.82 0.12 composition CaO MgO <![CDATA[K 2 The]]> <![CDATA[Na 2 The]]> <![CDATA[MnO 2 ]]> TS Content / wt% 0.78 0.39 1.84 0.28 0.05 3.41

[0051] (2) the first-stage calcined material and 98 wt % concentrated sulfuric acid were stirred and mixed uniformly, low-temperature calcined at 210° C. for 2 h, then heated to 400° C. at a heating rate of 5° C. / min and then calcined at high temperature for 1 h to obtain a calcined solid product and a second-stage flue gas, respectively, and the calcined solid product was naturally cooled to room temperature and then crushed to ≤2 mm to obtain a second-stage calcined material; wherein the mass ratio of the first-stage calcined material to the concentrated sulfuric acid was 1:0.2;

[0052] Using 5 wt % dilute sulfuric acid to absorb the first stage flue gas and the second stage flue gas until the sulfuric acid mass fraction is ≥ 90%, and the obtained sulfuric acid solution is reused as concentrated sulfuric acid in step (1) and step (2);

[0053] (3) mixing the second-stage roasting material with tap water, soaking the mixture in water at 80° C. for 1 hour, filtering the mixture to obtain a lithium leaching solution and a filter residue, washing the filter residue with tap water, and then drying the filter residue at 90° C. to a constant weight to obtain a leaching residue; wherein the mass ratio of the second-stage roasting material to the water for soaking is 1:3, and the mass ratio of the second-stage roasting material to the water for washing is 1:1.

[0054] Example 2

[0055] Lithium was extracted according to the method of Example 1, the only difference from Example 1 being that the mass ratio of the first-stage roasting material to the concentrated sulfuric acid in step (2) was 1:0.3.

[0056] Example 3

[0057] Lithium was extracted according to the method of Example 1, the only difference from Example 1 being that the mass ratio of the first-stage roasting material to the concentrated sulfuric acid in step (2) was 1:0.4.

[0058] Example 4

[0059] Lithium was extracted according to the method of Example 1, the only difference from Example 1 being that the mass ratio of the first-stage roasting material to the concentrated sulfuric acid in step (2) was 1:0.5.

[0060] Example 5

[0061] Lithium was extracted according to the method of Example 1, the only difference from Example 1 being that the mass ratio of the first-stage roasting material to the concentrated sulfuric acid in step (2) was 1:0.1.

[0062] Example 6

[0063] Lithium was extracted according to the method of Example 3, the only difference from Example 3 being that the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid in step (1) was 1:0.1.

[0064] Example 7

[0065] Lithium was extracted according to the method of Example 3, the only difference from Example 3 being that the mass ratio of lithium-containing clay ore to concentrated sulfuric acid in step (1) was 1:0.2.

[0066] Example 8

[0067] Lithium was extracted according to the method of Example 3, the only difference from Example 3 being that the mass ratio of lithium-containing clay ore to concentrated sulfuric acid in step (1) was 1:0.3.

[0068] Example 9

[0069] Lithium was extracted according to the method of Example 3, the only difference from Example 3 being that the mass ratio of the primary roasting of the lithium-containing clay ore to the concentrated sulfuric acid in step (1) was 1:0.4.

[0070] Comparative Example 1

[0071] (1) The lithium-containing clay ore powder (0.074 mm particle size content ≥ 65 wt%) and 98 wt % concentrated sulfuric acid shown in Table 1 were stirred and mixed uniformly, roasted at 210° C. for 2 h, naturally cooled to room temperature, and dry-milled to ≤ 200 mesh to obtain a roasted material; wherein the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid was 1:0.6;

[0072] (2) mixing the roasted material with tap water, immersing the mixture in water at 80° C. for 1 h, filtering to obtain a lithium leaching solution and a filter residue, washing the filter residue with tap water, and then drying the filter residue at 90° C. to a constant weight to obtain a leaching residue; wherein the mass ratio of the roasted material to the immersion water is 1:3, and the mass ratio of the roasted material to the washing water is 1:1.

[0073] Comparative Example 2

[0074] Lithium was extracted according to the method of Comparative Example 1, the only difference from Comparative Example 1 being that the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid was 1:0.7.

[0075] Comparative Example 3

[0076] Lithium was extracted according to the method of Comparative Example 1, the only difference from Comparative Example 1 being that the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid was 1:0.8.

[0077] Comparative Example 4

[0078] Lithium was extracted according to the method of Comparative Example 1, the only difference from Comparative Example 1 being that the mass ratio of the lithium-containing clay ore to the concentrated sulfuric acid was 1:0.9.

[0079] Comparative Example 5

[0080] The lithium-containing clay ore powder shown in Table 1 is used as a raw material, and lithium extraction is carried out according to Example 3 of Chinese Patent CN113293281A. The specific steps are as follows: 98% sulfuric acid and the lithium-containing clay ore powder are evenly mixed at a mass ratio of 0.9:1, roasted at 150°C for 2h, and after appropriate crushing (the lumps can be crushed), calcined at 800°C for 5h to obtain a calcined material; the calcined material is leached with water at room temperature at a solid-liquid ratio of 1:4 for 2h, filtered, and a leachate and a leaching residue are obtained respectively.

[0081] Comparative Example 6

[0082] The lithium-containing clay ore powder shown in Table 1 was used as a raw material, and lithium was extracted according to Example 1 of Chinese Patent CN109022772A, and the specific steps were as follows: 100g of lithium-containing clay ore was ground, and the grinding was 6.1% for +60 mesh and 55% for -200 mesh; the ground lithium mica sample was placed in a beaker, and 100g of concentrated sulfuric acid with a concentration of 98% was added and mixed well; 10mL of water was added and mixed quickly; the beaker was placed in a 150°C oven for 6h; the matured material was transferred to a leaching tank, 300mL of water was added to the matured material, the temperature was maintained at 80°C, and stirred for 2h; vacuum filtration was performed in a Buchner funnel, and 300mL of the filter cake was added after the filter cake was drained. The 60°C hot water is divided into three stages for disk washing. The first stage 100mL of washing water is combined with the leachate to prepare lithium carbonate. The second stage 100mL of washing water is returned as the next leaching agent. The third stage 100mL of washing water is returned as the disk washing liquid to participate in the next disk washing to obtain the leachate and the leachate residue respectively.

[0083] Comparative Example 7

[0084] The lithium-containing clay ore powder shown in Table 1 is used as a raw material, and lithium extraction is carried out according to Example 8 of Chinese patent CN114507779A, and the specific steps are as follows: the lithium-containing clay ore, sodium sulfate and calcium carbonate are dry-milled and mixed evenly in a mass ratio of 1:0.8:0.2, placed in a muffle furnace and calcined at a constant temperature of 750°C for 80 minutes, and after cooling to room temperature, the ball-milled calcined material is crushed, and leached with water at a solid-liquid ratio of 0.08 g / mL at 35°C for 120 minutes to obtain a lithium sulfate solution (leachate).

[0085] Comparative Example 8

[0086] 98% sulfuric acid and the lithium-containing clay ore powder shown in Table 1 were uniformly mixed in a mass ratio of 0.9:1, and calcined at 150°C for 2h; after appropriate crushing (the lumps can be crushed), calcined at 750°C for 5h to obtain a calcined material; the calcined material was leached with water at room temperature at a solid-liquid ratio of 1:4 for 2h, filtered, and the leachate and leaching residue were obtained respectively.

[0087] Li in the leached residues obtained in Examples 1 to 9 and Comparative Examples 1 to 8 2 O content, pH value of the leaching solution, calculated leaching residue yield and Li 2 The leaching rate of O is shown in Table 2, where the yield of leached residue (%) = 100% × dry weight of leached residue / dry weight of lithium-containing clay ore powder; Li 2 O leaching rate (%) = [1-(yield of leaching residue × Li in leaching residue 2 O content / 100×Li in lithium-containing clay ore 2 O content)]×100%.

[0088] Table 2 Li in the leached residues obtained from Examples 1 to 9 and Comparative Examples 1 to 8 2 O content, pH value of the leaching solution, calculated leaching residue yield and Li 2 O leaching rate

[0089]

[0090]

[0091] As shown in Table 2, by comparing the examples and comparative examples, when the total amount of concentrated sulfuric acid is 90wt% of the raw material, compared with the one-stage roasting process, the Li 2 When the total amount of concentrated sulfuric acid is 80wt% of the raw material, the Li leaching rate of the present invention using the two-stage roasting process is higher than that of the one-stage roasting process. 2 When the one-stage roasting process is adopted and the amount of concentrated sulfuric acid is 90wt% of the raw material, the leaching rate of Li 2 The leaching rate of O is 93.56%, the pH value of the leachate is 0.68, the leachate is highly acidic, and the subsequent lithium extraction and impurity removal requires a large amount of alkali, the lithium extraction process cost is high, and the excess sulfuric acid is converted into sulfate after alkali treatment and cannot be returned to the roasting process for reuse. Compared with the one-stage roasting process, the present invention adopts a two-stage roasting process, and the total amount of concentrated sulfuric acid is 60wt% of the raw material. 2 The leaching rate of O was 94.84%, and that of Li 2 The O leaching rate increased by 1.28%, and the amount of concentrated sulfuric acid was reduced by 30%. The pH value of the leaching solution was 2.46, and the acidity of the leaching solution was weak. The subsequent lithium extraction, purification and impurity removal costs were low, and the sulfuric acid could be reused. Compared with the existing sulfuric acid process, the present invention adopts a two-stage roasting process for Li 2 The O leaching rate is above 91%, and the Li 2 O leaching rate is high; in Li 2Under the condition of equivalent leaching rate, the present invention adopts a two-stage roasting process, and the total amount of concentrated sulfuric acid is reduced by more than 30%. The amount of concentrated sulfuric acid is relatively small, so that the concentrated sulfuric acid will not form a paste when mixed with lithium ore, and the mixture will not adhere to the roasting equipment to affect the roasting efficiency. The corrosion to the roasting equipment is small, and the leaching cost of lithium is greatly reduced. The lithium leaching solution obtained by the one-stage roasting process adopted in the prior art is highly acidic, and a large amount of alkali is required for subsequent lithium extraction and impurity removal, and the cost of lithium extraction is high. Moreover, the excess sulfuric acid is converted into sulfate after alkali treatment and cannot be returned to the roasting process for reuse; while the present invention adopts a two-stage roasting process followed by water leaching, and the pH value of the lithium leaching solution obtained is relatively high, and the amount of alkali consumed for subsequent lithium extraction and impurity removal is small, and the cost of lithium extraction is low.

[0092] In Comparative Examples 5 and 8, when sulfuric acid and lithium-containing materials are mixed and roasted at a temperature below 750°C, the generated aluminum sulfate will not decompose. Aluminum sulfate is a salt of strong acid and weak base, and the strong acid and weak base salt is acidic when dissolved in water. When the roasting temperature reaches 750°C, the generated aluminum sulfate decomposes into Al 2 O 3 and SO 3 Therefore, the roasting material leachate becomes weakly alkaline.

[0093] Example 10

[0094] XRD analysis of the roasted material showed that the mass ratio of the lithium-containing clay ore to 98 wt % concentrated sulfuric acid was 1:0.45.

[0095] (1) 110℃ sulphate roasting-roasting time test

[0096] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 110°C for 5 h, 6 h, 7 h and 8 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 110°C for different times are shown in FIG. Figure 1 As shown. Figure 1 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, the lithium-containing mineral peak still exists after roasting at 110°C for 5 to 8 hours.

[0097] (2) 130℃ sulphate roasting - roasting time test

[0098] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 130°C for 3 h, 4 h, 5 h and 6 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 130°C for different times are shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 130°C for 3 to 6 hours, the lithium-containing mineral peak still exists, but the peak intensity is weakened.

[0099] (3) 150℃ sulphate roasting - roasting time test

[0100] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 150°C for 2h, 3h, 4h and 5h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 150°C for different times are shown in FIG. Figure 3 As shown. Figure 3 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 150°C for 2 to 5 hours, the lithium-containing mineral peak still exists, but the peak intensity is further weakened.

[0101] (4) 170℃ sulphate roasting-roasting time test

[0102] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 170°C for 1 h, 2 h, 3 h and 4 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 170°C for different times are shown in FIG. Figure 4 As shown. Figure 4 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 170°C for 2h, the lithium-containing mineral peak is significantly weakened.

[0103] (5) 190℃ sulphate roasting - roasting time test

[0104] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 190°C for 1 h, 2 h, 3 h and 4 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 190°C for different times are shown in FIG. Figure 5 As shown. Figure 5 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 190°C for 2h, the lithium-containing mineral peak is significantly weakened.

[0105] (6) 210℃ sulphate roasting - roasting time test

[0106] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 210°C for 1 h, 1.5 h, 2 h and 2.5 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 210°C for different times are shown in Figure 1. Figure 6 As shown. Figure 6 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after calcination at 210°C for 1h, the lithium-containing mineral peak is significantly weakened.

[0107] (7) 230℃ sulphate roasting - roasting time test

[0108] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 230°C for 0.5 h, 1 h, 1.5 h and 2 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials obtained by calcining at 230°C for different times are shown in Figure 1. Figure 7 As shown. Figure 7 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 230°C for 0.5h, the lithium-containing mineral peak is significantly weakened.

[0109] (8) 250℃ sulphate roasting - roasting time test

[0110] The lithium-containing clay ore shown in Table 1 was mixed with 98 wt% concentrated sulfuric acid, and calcined at 250°C for 0.5 h, 1 h, 1.5 h and 2 h, respectively, and naturally cooled to room temperature to obtain calcined materials. The XRD analysis results of the calcined materials calcined at 250°C for different times are shown in Figure 1. Figure 8 As shown. Figure 8 It can be seen that when the mass ratio of lithium-containing clay ore to concentrated sulfuric acid is 1:0.45, after roasting at 250°C for 0.5h, the lithium-containing mineral peak is significantly weakened.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting lithium from a lithium-containing material, It is characterized in that The following steps are involved: The lithium-containing material is mixed with the first concentrated sulfuric acid and subjected to a first stage of roasting to obtain a first stage of roasting material and a stage of flue gas; the mass fraction of the first concentrated sulfuric acid is ≥90%, and the mass ratio of the lithium-containing material to the first concentrated sulfuric acid is 1:0.1-0.5; the temperature of the first stage of roasting is 150-250°C, and the holding time is 0.5-3h; The first stage roasting material is mixed with the second concentrated sulfuric acid, and two stages of roasting are performed to obtain the second stage roasting material and the second stage flue gas respectively; the mass fraction of the second concentrated sulfuric acid is ≥90%, and the mass ratio of the first stage roasting material to the second concentrated sulfuric acid is 1:0.1-0.5; the two stages of roasting include low-temperature roasting, heating and high-temperature roasting in sequence; the temperature of the low-temperature roasting is 150-250°C, and the insulation time is 1-3h; the temperature of the high-temperature roasting is 380-550°C, and the insulation time is 1-2h; The second-stage roasted material is water-leached to obtain a lithium leaching solution.

2. The lithium extraction method according to claim 1, It is characterized in that The heating rate of the heating is 5 to 10° C. / min.

3. The lithium extraction method according to claim 1, It is characterized in that The mass ratio of the second-stage roasting material to the water for soaking is 1:2-4.

4. The lithium extraction method according to claim 1 or 3, It is characterized in that The water immersion temperature is 15-100° C., and the time is 0.5-2 hours.

5. The method for extracting lithium according to claim 1, It is characterized in that After the first stage of roasting, the obtained roasted solid product is crushed to a particle size of -0.074 mm with a content of ≥40wt%.

6. The method for extracting lithium according to claim 1, 2 or 3, It is characterized in that The second stage roasting also includes crushing the roasted solid product to ≤2 mm.

7. The method for extracting lithium according to claim 1, It is characterized in that The lithium-containing material includes one or more of lithium-containing clay ore, lithium mica concentrate and spodumene concentrate high-temperature roasting pre-treated material.

8. The method for extracting lithium according to claim 1, It is characterized in that The first stage flue gas and / or the second stage flue gas are absorbed by dilute sulfuric acid to obtain a sulfuric acid solution; when the mass fraction of the sulfuric acid solution is ≥90%, it is recycled as concentrated sulfuric acid in the first stage roasting step and / or the second stage roasting step.

9. The method for extracting lithium according to claim 1, It is characterized in that The pH value of the lithium leaching solution is ≥1.5.

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